Hi Jenna's mum. I went thru this a couple of weeks ago although by dd is older. I was hoping there would be some magical quick fix- but as a first time mother I have learnt that all it takes is alot of hard work, consistency and patience!
Each time dd rolled onto tummy and then cried for me, I would go in, avoid eye contact, no conversation, roll her back, re-tuck in and say the words 'it's time to go to sleep' and leave the room immediately. Sometimes she rolled over b4 I even got to the door but I would leave her, wait 3-5 mins (crying by then) and go in and do the same thing. The 1st time took about 30 mins of going in & out like a yoyo. But I just kept doing the same thing, in the same order- by about the 4-5th day she got the message. She still cant roll back and she's 8.5 mo- so I revert to plan as above if it happens again now.
In regards to DF- been there too. Have you started to reduce the amount of milk for her DF? She probably not eating that much becoz is full on the milk. At 6.5 mo she should be ready for solids. I dropped amount of formula by an ounce every 2-3 nights until I got down to about 4 ozs. bottle then one night I fell asleep on the couch and woke at midnight- too late for a DF so I left it to see what would happen. Didnt wake and never gave it again. So then she was waking hungry and having her milk and solids in the morning and the requirement for the DF was broken.