10 month old can't go from lying flat to sitting

[Studentmumm]

Hi.
My lb is almost 10mth now, he is sitting unaided, going from sitting to crawling and vice versa, crawling and actively trying to pull himself up.
He's never rolled over, we have encouraged him but he's scared to do it and I don't want to upset him. He can't go from lying on his back to sitting position and I'm starting to get worried even though he's doing well in other areas this seems to concern me.
I didn't go into labor and Harris was in NICU for 2 weeks after us both almost dying and bcos of that he goes for check ups at the hospital ever 4 month for neurology and physio, every time I go they also show concern he is unable to roll over, they told me he couldn't crawl or walk if he couldn't roll which is rubbish bcos he can crawl and is dying to stand up so I am proud he's got there even though professionals said it was unlikely he would
He has always slept on his back never rolled over at all to his side or his tummy to sleep and he gets really frustrated when he wants to sit up but has nothing to pull himself up on.
I guess I'm on here as a last resort to ask if there were any other children who were in a similar situation to myself and how the parents handled it?
Tia x

Yes sorry I should have mentioned, he had an MRI scan at 6 days old and it came back with focal points of concern, white matter which lead to the continued check ups at the hospital

And thank you guys for the reassurance, sometimes after leaving the hospital with the news they give you it worries you more!

Also, I did mean getting from lying flat to sitting, as in going onto his side (like a roll) and pushing up to sitting. Not an actual sit up, that's what he tries to do then gets really frustrated lol! Wee scone 🙈

The physio last week told us to do some exercises when changing his nappy which we try to do but when we do them he flips over and gets scared 😂 but we continue to do it yes knowing that it should help him 🙈