Losing Weight after giving birth - first time Mum

Hi there, after giving birth 10 days ago because of many implications both baby and I had to stay in hospital for a week and just got out last Friday . Im on blood pressure tablets due to complications and although cant breast feed at moment due to meds I'm expressing.

I've put on 4 stone and naively thought I'd lose most of it the first week but that's not the case. If I don't eat something every couple hours I'm getting very faint, need to keep my energy up due to being up most of night and have been told by midwifes and doctor that I am unable to exercise for 6 weeks not even walking .

I really want to make a start and appreciate ANY tips, advice or friend requests so need motivating as exhausted and need a boost!

Thanks!!