I can't help it!!!!!!!!

I can't help it! I have a broken rib right now and am in so much pain sleeping on either side. I fall asleep propped up and I wiggle down and before I know it, I'm sleeping almost flat on my back. I'm 35 weeks 1 day and know this is a no no but there's literally no other way :( I've always been a back sleeper, so even before the rib issue, I was waking up on my back. Can anyone relate with previous pregnancies and had all be well???? I'm sure it's fine but I can't help but feel weird about it! She moves around all the time even when I'm on my back.