I'll probably get flames for this my my ds2 has slept on his front since birth. He honestly, no matter how hard I tried, would not sleep on his back. Then I think he was just more comfortable on his front because of his reflux. The mw was ok with it actually. He had great head control from birth and mw said he must just be a natural tummy sleeper. I still worried like hell at the beginning though.
My ds1 started sleeping on his tummy around the same age as your dd. He could roll both ways by that point so I just left him to it. He's 21 months now and I still peek in on him to find him asleep on his tummy with his bum in the air.
My DS2 has never slept on his back - ever. He is 2.9 now. Even when he was tiny, hed shuffle somehow to his side and when he could roll he slept face down ever since. I was concerned at first. But nothing I ever did (even rolls of blankets either side to chock him on his side) ever worked.
Can't advise but just wanted to let you know at least one other baby hates the back thing for sleep!
I think some babies are natural front sleepers, they naturally have good head and neck control. Other babies are natural back sleepers, who if put on their front would be at serious risk from suffocating. Natural back sleepers have a bald patch on the back of their head which is very defined as they only move their head very slightly.
I've had both, I allowed my front sleeper to sleep on her front, only now I wish I hadn't woken every hour through the night to check she was still breathing. If I had to do it again I'd be much more chilled, especially if she were rolling on her own!
I had a baby in the NNU where they rotate them on a regular basis to prevent sores. When we got home she refused to sleep on her back. We spoke to the paediatrician about it and he said that it is fine as we're low risk (no smokers, don't drink or take medication and she was breastfed) anyway.
Front sleeping is more natural to babies (that's why they end up with bald spots, back sleeping is not normal) but there are more risk factors in our lives these days. Anyway, once they're rolling for themselves they're fine to sleep how they want to (in my children's case that's head to toe, standing on their head, across the bed, foot through the bars and on the floor...)
Thanks for the reassurance guys. I must admit I was pretty worried for the first month or so as she could roll from her back to the front but not the other way. Now that she can roll both ways I'm a bit more relaxed.