Your body will tell you when its not okay anymore... my mom always gets on me for squishing her grandchildren. Its never caused a problem for me ♡ good luck!
I'm not 100% sure, but from what I've read is to try to sleep on your side, left is best. If you wake up on your back or another position don't worry, we can't control what we do in our sleep. Just adjust when you notice.
They say it's fine as long as your comfortable. I sleep like that too but I'm only 20 weeks I usually stop once I get to big to do that cuz its not comfortable anymore