My 4 month old has begun rolling from back to front and is now showing a strong preference for sleeping on her side and/or stomach. She uses a sleeping bag. We are currently getting up multiple times a night to roll her onto her back but she immediately rolls back onto her side/stomach again. She is not rolling from front to back yet but we are doing a lot of tummy time to try and build up her strength. Any advice on what we can do going forward? We’re exhausted and she is getting upset that we’re disrupting her so much. Thanks!

Most babies will be rolling over by 4- 5 months. Some earlier, some later.
This is very normal as babies grow & become stronger.
Many babies then prefer to sleep on their side or tummy.
This is not something that needs to be stopped. It is important to make the “new” environment as safe as possible.
https://rednose.org.au/article/what-do-we-do-now-that-a-baby-has-started-to-roll-over

Is her sleeping bag one with arms out?
Is she in a cot or still in bassinet?
Babies need arms free & the space of a cot to roll well.

Good to see you are increasing tummy time when awake.
This helps to build upper body strength.
Does she have good head/neck control?
Is she reaching for toys when on tummy?

Still always place baby on back for sleep.
Parents are not expected to sit up all nigh