I sleep on my belly and it's super comfy. Midwife said it's fine. I did the same last pregnancy. Sometimes on my side, I can feel a body part sticking out and if I shift a little or prod the baby. I can get him to move a little, so we're both more comfortable.
If it hurts you then it may hurt baby but baby is still well protected. Being uncomfortable and feeling baby wriggling around is normal. They adjust their position as we adjust ours. Mine gives a wriggle every time I turn over in bed.
Unless you're attempting to lay completely on your stomach I don't think you'd do any harm. I still lay somewhat angled onto my stomach with one leg tucked up to take the pressure off.
I tend to sleep on my side, slightly leaning forward with my top knee out to stop me rolling completely forward. I then have a pillow going under my belly down to under my knee with a second pillow on top under my knee so I am really propped up.
xxx