20 week scan.

I had my 20 week scan today. Baby is doing very well but I'm the one with the issue. My fetal and medicine doc is worried about my csection scar. My placenta is completely anterior and i have an abnormality in my scar, I'm at risk for rupture, and what i thought was the baby this entire time giving me pressure has actually been contractions. I had several contractions at my scan and I've been contracting several times a day for weeks now. I originally was scheduled for another csection at 39 weeks but now they want me to do it at 36 -37 weeks because they don't want the baby to get big and don't want me to rupture. Ive only had 1 csection so that dont know why this is happening but I'm worried my baby is going to be really small or something. :(