You need to start cruising for mum friends - and fast.
Thank goodness for my NCT group, who helped me stay sane in that first year of being a parent. Even though I suspect their kindness to me initially stemmed from pity (I was the cricket widow whose fiancé announced he was 25 years old to the class before failing to turn up to any subsequent session), our group just hit it off.
I remember when we rolled our eyes (happily, we were a cynical bunch) when the NCT teacher said we'd be friends for years to come, but truer words were never spoken.
We've stayed in touch despite moves (to another continent, in one case), and now that our children are older, our hangouts have got even better: we've swapped baby cinema for spa days and boozy lunches (and they're still all ears when it comes to talking about baby rashes, toilet habits or sleep cycles).
Over the past few years, there have been times when I've felt lonely and isolated, both from my university friends who were making exciting career moves and having spontaneous social outings that I could only organise weeks in advance, and from other mothers, who seemed to have it figured out when I felt like I was barely hanging on.
Part of my social insecurity stems from working from home - while there are plenty of advantages, being a work-from-home parent doesn't do you any favours when it comes to expanding your social circles.
But I'm learning that you can make friends anywhere (and I mean, anywhere!), and that like with any friendship worth having, it's about the quality and not the quantity.
At one stage in my pursuit of mum friends, I used to seek out mums with dogs, thinking that would be an extra thing for us to bond over, until I realised Bolshy the bulldog is so badly behaved and requires so much TLC that no one can commiserate with me on that one.
I have met some amazing mothers, often by accident. As with dating, mothers pick up other mums wherever they can: parks, playgrounds, baby groups, dance classes...
You can even meet mum friends at the dry cleaners: My most successful pick-up to date was actually the result of my husband hearing an American accent and practically shoving me into a mother and her daughter in our local dry cleaner. She turned out to be a fellow New Yorker who lived in our building.
And since her daughter is one year older than mine, she taught me everything I needed to know: What Team Umizoomi is. That there is a chicken pox vaccine you can get in this country. And most crucially, that when you have girls, the purple phase comes before the pink one.
Now that D has started school, I'm finding there are lots of mums I can talk to, not just about the kids, but juggling work with family, discussing our own childhoods, exchanging business ideas and recommending favourite TV programmes. And it feels really lovely to meet people who live nearby and are going through similar things at the same time as you.
When I got invited to a coffee morning the other week, I felt my cheeks flush with excitement.
Because even when you're a parent, sometimes you feel like you're back at school and you just want to belong somewhere, whether it's with the athletes, the thespians or the Goths.
I think I'm finally finding my people.
Have you made close friends since becoming a parent?