6.5 month old struggling with reliability rolling tummy to back. Phyio exercises are making him miserable. Do I just let him do it in his own timeline?

FTM to a sweet 6.5 month old baby boy. He had severe reflux till 4 months which made it nearly impossible to do tummy time with him (he threw up and hated the position so much because of reflux). He learned how to roll onto his tummy at 5.5 months and now constantly gets into tummy time himself. He also sleeps on his tummy and it's become his favourite position. However my boy can only tolerate it for so long and starts to scream and cry because he cannot roll back to back from tummy. He can only do it like 20-30% of the time (so yeah he does actually know sort of how to do it but just doesn't manage to do it all the time). The rest of the time he cries and screams for us to rescue him. This means we rescue him over night and we wake up a few times and constantly during the day in his wake windows because he goes on his tummy on his own within second of being put on the floor but screams after 10 minutes. We took him to a PT based on his doctor's recommendation just to help him out a bit to be able to learn the skill faster. They gave us exercises which we are told to do every wake window and it's quite a bit.

I am struggling so much and so is the baby. I get no time to myself now because I am basically spending his entire wake window with him doing workouts. The PT really gave us a lot to do which basically translates to all his wake windows completely. The rest is consumed by basically him eating solids. He is severely unhappy and basically cries the entire wake window. He is attempting to crawl now and me spending his wake windows to do workouts on him makes him mad almost that I am intervening.

So I ask, how big of a deal are these milestones? Considering he can move well on to his tummy and can do it occasionally back to his back on his own, do I need to really be worrying about the milestones and how he is late to master it yet? I accept to just help teach him and rescue him as needed whenever. I just don't want this baby to be this miserable and he wants to just do things on his own. I am confident his rolling was impacted directly by the fact that he was not able to do much tummy time until his reflux improved and now my poor baby is just trying to catch up. This is my first baby so I don't know how big of a deal this motor milestones are. He is 10/10 on every other milestone.