Sitting up?

Breana • Had my rainbow on 12.4.19 💕🌈 Miscarried 12.14.18 👼🏼

My daughter will be 7 months this week and she can’t seem to get the hang of sitting up... she’s rolling ALL OVER THE PLACE but has no interest in sitting up unless something is supporting her back... but I know babies that are younger than her by as much as a month that are already sitting... is this normal? Can I do anything other than just sit with her and let her learn to slowly be able to hold herself up?