I sleep on my side, i started praticing when i was 4 months but usually side is the only way. N the way my body supports my belly is half belly n side i duno its hard to explain. Good luck!
I've heard some women use a pillow between their legs and one under the tummy. I just use a big blanket and put it under my stomach and that seems to reduce the stress on my back. I can't wait to be able to sleep on my stomach or my back again lol