For fourteen years, I thought it was my fault.

The photo

There's a photo from my sister's wedding that I've never shown anyone. I'm in a navy dress I bought two sizes up, holding my clutch bag flat against my tummy with both hands. I'm smiling. I remember exactly what I was thinking: please don't let anyone notice.

I was 41. My youngest was seven.
And I still looked pregnant.

The years nobody talks about

I had my three children in six years. Sophia, then Marco by emergency C-section, then Ella. I was exhausted, I was happy, and I believed my body would come back the way everyone said it would.

It didn't. My face came back. My arms and legs came back. My tummy stayed: soft, low, sitting forward over my jeans, whatever I did.

So I did everything. I counted calories for years. I did sit-ups on the living room floor after the school run, hundreds of them. I bought the shapewear, the waist trainers, the wraps that rolled down by lunchtime and left red marks by dinner. Every one of them made the same promise. Every one of them made me feel a little worse when it didn't work.

The people who loved me said kind things that didn't help.

• My husband, Tom“You look lovely. I honestly don't know what you're seeing.”
• My friends at the school gate“It's just a mum tum, we've all got one.”
• My GP, after two minutes“Try to lose a bit of weight and do more core work.”

So I stopped talking about it. I chose my clothes around it. I stood at the back of every photo. I said no to the swimming pool with my children more times than I want to admit.

The word nobody had said

Back home in Leeds, I booked an appointment with a women's health physiotherapist. She asked me to lie down and lift my head, then pressed her fingers into the middle of my tummy. They sank in.

Three fingers wide.

“You've got diastasis recti,” she said. “Your tummy muscles separated during pregnancy and never fully came back together. This isn't fat. And all those sit-ups may have made it worse.”

Fourteen years. Nobody had ever said that word to me.

I cried in the car park. Not because it was bad news. Because, for the first time, it wasn't my fault.

Making the one I couldn't find

I went looking for something that would do what Nonna's band did, but that I could wear under my work trousers on an ordinary Tuesday. It didn't exist. Everything squeezed the front and pushed the rest out at the sides, or rolled down the moment I sat.

So I started making it myself. A high waist that sits above the navel, well clear of a C-section scar. A band that crosses over the front, like hers. A seamless knit that holds you all the way round, front, sides and back, and stays put when you sit, bend and pick up a toddler.

It took two years and more samples than I can count. My sister tried every one. Then the mums from the school gate. Then their sisters. When women I had never met started messaging to ask where they could buy “the crossed one”, I named it after the woman who started it all.

Venialli.

The letters

Today, women write to me every week. Women weeks after a C-section, and women whose last baby is at university. Women going through the menopause who suddenly don't recognise their own shape. Almost every message starts the same way: “I thought it was just me.”

One of them, a mum of six, wrote:

I read that one standing in my kitchen, and I thought of Nonna sitting me down in hers.