My DD is put down to sleep on her back. She immediately turns to her side or back. When she's asleep, we turn her back before we go to bed ourselves but in the morning she's always on her front, knees bent with her backside in the air. Is she old enough for me to stop worrying and just leave her? And if so, should I stop turning her before I go to bed? (It wakes her up a bit but usually doesn't cause problems).