This month my eldest child turns 10. So I am supposed to embarrass myself by saying things like: “My baby’s all grown up. My baby’s 10 years old.” Which I will say. Because it’s exactly how I feel. I never wanted to be the person who thought such a thing to themselves, let alone said it out loud, like some middle-aged matron (which is, of course, what I am). But, the trouble is, it’s true.

Like every idiot across the history of time confronted by the mystery of the passing of time, the fact of our mortality and the reality of my son having a larger foot than my own, I can’t believe that my baby – my first child, Will – has become an actual person. How dare he?

I am amazed and disbelieving that this has happened. Perhaps what I can’t believe most of all – and what I don’t even want to say – is that in less time than the time I have known Will, he will not belong to me any more. And, although 10-year-olds still need plenty of looking after, perhaps he already doesn’t need as much.

Worse, I have been a parent for 10 years. It’s a (much wanted) job I have had to grow into, a job that 10 years ago I had no experience of and no idea how to approach. Actually, I had quite a lot of ideas about how to approach it. They were just useless when faced with an actual child.

They say you make all your mistakes on the first child, who has to endure the indignity of watching you become a parent for the first time. Sorry about that, Will. But we all learn by trial and error, improving, slightly with each one. With apologies to Will, (nearly) 10, Vera, seven, and Jack, three, for all the mistakes, here’s what I have learned over the 10 years.

Don’t bother with guilt (too much)

This is one for all parents but for mothers in particular. Working parents feel bad about working. Stay-at-home parents feel bad about not working. (If you don’t ever feel bad about anything then well done! Do tell us your secret. Or probably don’t.) A parent’s place is in the wrong and rightly so. Parenting is the most responsible and privileged job in the universe. If you mess it up you get to ruin someone else’s life; often unintentionally and by accident.

I can remember crying with the wrongness of working in the days after Will was born but also feeling grateful that I would not have to “go back to work”. (I’m freelance. So I never took maternity leave, I just worked around them.) I saw other mums (and dads) frozen with anxiety about getting back to the commute after blissful weeks or months of nothing but baby. And I’ve heard stay-at-home mothers say quietly and privately how bad they feel about not making their own money. No one has it perfect.

I find it hard to believe the statements of the likes of Davina McCall who, asked about the secret to being a successful working parent, confidently say, “I don’t do guilt.”

But I do admire it and bear it in mind. Imagine what you could do with all the time you’ve saved if you didn’t waste it feeling guilty and inadequate.

Don’t try to make your child your friend

This does not mean you have to be their enemy. You are their friend (and greatest advocate and supporter). But they are not your friend. Children aren’t stupid. Who wants to be friends with the most excruciatingly embarrassing person ever? That person is you.

Don’t be a mother or a father. Be a parent

It took me a long time to figure this one out. OK, yes, some tasks are gender-specific. Outsourcing birth is a distant goal. And we will not get into the NCTteacher who spent two hours trying to convince an open-mouthed group of expectant parents that men are equally capable of breast-feeding: “You just need to have the right mindset and lactation will spontaneously occur.” She added: “It’s really beautiful. There are many documented cases.”

I spent many long hours online trying to find these documented cases as I was desperate to meet these “mind-over-matter”, milk-producing men. But my search only yielded obscenities and an Australian spoof documentary entitled The Milk Men.

There are many tasks of mothering and fathering that are important. But without getting too PC about it, most of these tasks do not need to be allocated to a person of a specific gender. All that matters is that these things happen.

The things that need to take place most often definitely count as “parenting” not “mothering” and women shouldn’t have a monopoly on them: loving your child to bits, hugging your child so hard they can’t breathe. Anyone who wants mastitis is welcome to it.

Don’t fight over the role of primary parent

The best and worst thing that ever happened in our house was when we tried to do “equally shared parenting”, an American thing where you split everything down the middle, right down to one person washing darks and another washing whites. I realised that I was doing far less than I claimed. Simon (my husband) realised he was doing far more than he imagined.

The happiest households I know have worked out whether there is a primary parent. If there isn’t, then you’re both equal parents and no one tries to take ultimate charge and instead you try (usually ineptly and with a lot of resentment) to share everything. In the unhappiest two-parent households I know, one person is the unwilling, put-upon primary parent and the other person is the blissfully unaware secondary parent. Know who’s doing what, which camp you’re in and make your peace with it.

Other people know nothing

Not strictly true. Sometimes they know something. But no one knows your children like you do. And no one knows your life circumstances. No one knows the reasons why you are the kind of parent you are, the compensations you’re making which stem from your own childhood and the stuff you do because it keeps your relationship together. (I am not talking about weird sexual stuff. There is no time for this. Or if there is, then do write a Fifty Shades book about it and become a multi-millionaire. Your children will be embarrassed but they will get to live in a massive house and have no university debt.)

Beware other people’s parenting advice (including that contained here). No one, not even Supernanny, has all the answers. And most of the people who put themselves up as supernanny figures do not have children of their own.

What works in one family doesn’t work in another. Listen to everything out there and weigh it up, test it out and discard it according to your own experience. Most important: if there are people who really look like things are working out great and they have all the answers, you probably don’t know them very well.

You have made your bed. Now lie in it with a smile on your face

You had these children and you cannot put them back. Yes, everyone tries to count their blessings but it’s not always easy. Instead much fuss is made about how parenting makes you “insane”. There’s a great trend among parents (and mothers at the school gate in particular) to go in for competitive “bad parenting”, with much hilarity about “wine o’clock” being pulled forward to 4.59pm and being so disorganised that – horrors! – you forgot to get in an allergy-conscious, wheat-free substitute bread for the playdate.

But it is this stuff – and not the actual children – that drives me quietly mad. Because a lot of it hides passive aggressive resentment about parents feeling that they have to be more heavily involved in their children’s lives than possibly they’d like to be. If you really don’t want to do stuff, find a way to not do it. You chose this life. Make it work so you are not boiling over with anger and hate.

When things go wrong, find an upside. As Amy Chua writes in her much-maligned parenting manual, Battle Hymn of the Tiger Mother, at least if you run over your child’s foot while reversing the car, the resultant surgery will mean they have plenty of time to practise the piano. (Disclaimer: you don’t always have to make your bed. But teach children to make theirs.)

Measure life in sleeps

I cannot know whether it is possible to convince teenagers of the value of this, but there is endless joy to be had in measuring life out in sleeps. “How many sleeps until …?” is the best question ever and no one in this house is giving it up any time soon.

Remember how old your child is

I don’t just mean remember their birthday. Although you must try to do that. No, what I mean is this: endeavour to provide age-appropriate parenting. This is really difficult. I still nearly buy Thomas the Tank Engine things for Will because he loved them so much about eight years ago. You never fall out of love with the baby you first met and you revisit those memories like a lovesick junkie. But you fall in a different kind of love with the person your child grows up into, even if all they want to talk about is the Napoleonic wars, Games Workshop and diggin’ it Minecraft-style.

Today is not coming back

It has become a great Oprah-endorsed truism that we are all supposed to “live in the power of now” and “embrace the moment”. But it is a truism for a reason. The one thing that spending time with children teaches you more than anything is that all we have is this second, right now. What happened before and what might happen later are irrelevant and, actually, non-existent. Children, especially the littlest ones, live exclusively in the moment and unless you can join them right there, you will not have spent any time with them at all.

I can’t know if I would feel the passing of the years differently if I weren’t a parent. But it makes me feel like I’m in a time-lapse nature documentary and not in a good way. I enjoy moaning in a despairing voice, “How did you get to grow up so big?” And the children enjoy responding, wearily: “Mummy, you know how. Eating. And birthdays.” That is the key to it all. No more eating and no more birthdays and then I will stay young and they will stay babies for ever more and everything will be fine. Many happy returns for next week, Will. But after this, promise me: no more eating and no more birthdays.

Teenagerdom is another planet and I have delayed my passport application

I am fascinated and terrified by the hooded, zombie eyes of the parents of teenagers who look down at children under the age of 10, look up at the parent in charge and hiss this warning: “Enjoy this time. You have no idea.”

I have tried to say to these parents of adolescents in my best Oprah voice, “Today is not coming back.” But I gave up after one of them tried to punch me.