First baby advice

My baby will be 5 months in a few days & she has little to no interest in wanting to roll over. Rather it’s back to stomach or stomach to back. Now she did roll from stomach to back one time in her doctor office at her 4 month Appt but that was the Last time. She can however get to her side when she’s sleeping or following someone with her eyes being nosey. Should I be worried? Or call her doctor? When does a baby usually start rolling?

*she was born a premie at 34 week*