Rolling back to tummy but not tummy to back

My baby is 21 weeks (17 weeks adjusted, she was a little premature) and just started to roll from her back to her tummy but hasn’t figured out how to roll from her tummy to her back yet. This would be fine except 1) it freaks me out that she could roll onto her tummy at night and not be able to roll back and 2) she HATES being on her tummy but seems like rolling so she keeps rolling onto her tummy and then gets pissed off because she can’t figure out how to roll back.

She gets plenty of tummy time but she just hasn’t been able to figure out what to do with her arms to roll onto her back. Instead of pushing herself up she just shoots her arms straight back and flails her arms and legs while getting increasingly frustrated. I know she’ll figure it out eventually but, ugh, it’s hard to watch her struggle so much!

Anybody else dealing with this?