I would say sleep sitting up.and dont drink water before you go to bed.
You don't say how far along you are, but I think the in between stages are almost the most uncomfortable. When you tummy is not big enough to rest on the bed when you sleep on your side, but is big enough that you know something is there. I found it helpful to wedge a fairly flat pillow under my tummy when laying on my side. That way you have some support, so your muscles can relax while you fall asleep.