Nope you will be fine. After all it is not possible to control what position you move into when you are asleep.
Think about when people break a leg or something, when they sleep their body kinda self protects and doesn't move that side much.
Your body will self protect too and sleep however is comfy, when you aren't safe to lay on your belly lol you won't be able to cuz your bump will be in the way.
You know those pillow things you can get that are like a wedge - pop the shallow end under your belly and that helps, more often than not I sleep almost in the "recovery position" which is kinda half on side and half on belly.
Remember that you are
not laying "on" the baby, cuz it is inside you not under you.
Laying on your left side helps increase blood flow to the uterus and improves respiration apparently.
But the most important thing is to be comforatable, when you are comfy and relaxed so is baby
big hugs jess