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I feel there is some hormone imbalance and it could be the reason for the miscarriage too.
Your weight is more than expected. This extra fat will be converted into hormones in the body. This hormone can prevent or delay ovulation, could be the reason for the delay in periods.
The inner lining of the uterus will start getting detached on its own. This would appear as bleeding of different severity and as it tries to come out will cause cramps. This is what you are experiencing.
You should get bleeding in the coming days, with thick fleshy masses. This is common after miscarriages. So just relax, this will get corrected over next few months.
Over these months, try to be as active as possible and have controlled diet. Your weight will reduce over time, and this hormonal imbalance will get corrected. All the best.
For further information consult an obstetrician and gynaecologist online --> https://www.icliniq.com/ask-a-doctor-online/obstetrician-and-gynaecologist