Stomach muscles post hysterectomy

[thisnotsodarkevening]

I had a total abdominal hysterectomy 3 years ago. I have a big stomach which I thought I would lose once I had the OP (It was for large fibroids). I didn't though and now, despite exercising 5 times a week and eating healthily, I just can't tone up there. My mum reckons that this happens after a hysterectomy because they have to cut through your stomach muscles??

Does anyone know if this is true? Or how I can get a flatter stomach? It's starting to get me down, to be honest.

Thanks.