Your DD2 is still very young and it can take a long time for your body to get back into feeling normal. That said, now is not too soon to see a physio about your tummy muscles and this should hasten your recovery.

WRT the prolapse, have you had your 6 week check yet? If it's not soon then please make an appointment tomorrow to get checked and referred to someone who can help you. There are treatments for prolapses, not all of them surgical. Once you have been treated you will be able to find out if a 3rd child is a possibility or not but for now you need to concentrate on getting better.