Help! Overweight Vbac?

I had a cesarean with my first due to breech presentation. She came a month early (not sure if that matters). I was 144 when I got pregnant the first time and I got up to 185 during the pregnancy. After giving birth I got up to 240 and after a few months of hard work I'm hovering around 200 (I'm 5'4") and actively TTC. Do I have to be under a certain weight for vbac? Should I put off TTC until I reach a certain weight? What are my chances of having a success and what would better my odds? Any girls who have had similar situations please tell me your stories (even the scary ones), I'd rather be prepared!