Not rolling over

My LO will be 6 months this week and she still hasn’t mastered rolling from back to belly!

She rolled from belly to back very early at 2 months (consistently, it wasn’t a fluke!). But I’ve started noticing in this past month that she really doesn’t even do that anymore. When she does tummy time, she’ll prop up on her elbows and look around and eventually cry, but won’t roll. And on her back, she’ll roll to her sides but never fully over. She only accomplished it once fully from back to belly.

I had wondered if she’s just very focused on other developments like sitting, that she’s over trying to do the other things? She also is a very large baby, measuring 99th percentile for weight and height, so I wondered if it’s harder for her to maneuver because of this? I’m just concerned and wondered if anyone else has been going through this too?

Thanks in advance!