When the girls were babies, the problem was always right in front of me and the fix was right in my hands — literally. Crying? Pick her up. Hungry? Feed her. It was exhausting but simple. Now my girls are five and six. They sleep, they dress themselves, they pour their own cereal (everywhere). The physical stuff is so much easier. So why do I feel more stressed than I did with newborns? Because the worry changed shape. It used to be about keeping them alive. Now it's about keeping them okay — and "okay" is so much harder to measure.

This is the tender one. I talk honestly about the part of parenting nobody warned her about: the letting go. The six hours a day I have no view of. The feeling of being "made redundant" from a job I was really good at. And the thing keeping me up at 2am now — girl friendships, the "mean girls" I know my daughters will meet one day (not now — right now things are good — but one day), and the memory of being nine years old myself, standing at the edge of a playground watching my best friend laugh with someone else, and never telling my mum.

I don't have a fix. I'm honest about that. I'm winging it, same as always. But if you're lying awake at 2am thinking about this stuff too — I get it. I really, really get it.

• "It used to be about keeping them alive. Now it's about keeping them okay."
• "How do you check if your kid's heart is okay? You can't."
• "I feel like I've been made redundant."
• "When they're babies you worry about their bodies. When they're bigger you worry about their hearts."