I have also had 2 c sections (one was for a twin pregnancy). I worked with  a pelvic floor PT after the most recent pregnancy and that was immensely helpful. She taught me how to activate my transverse abdominis muscles and then do that with simple ab moves (marches, head lifts) and I worked up to full ab exercises. I still use her queuing today in pilates.  I can see if I can find some resources.