Baby with a lopsided head?

she is 7 mo. old now and since she was a newborn she has always preferred to look to the right when sleeping or relaxing. when you look at her, the left side of her head sticks out further. For the last 6 months we've tried using head positioners, using infant positions-turning her on her side tilting her to the left thinking she might just look that way, and even went as far and rigging up her mobile so it hangs down low on her left side. We've tried turning her swing when she watches her einstein movies so she's forced to look to the left and that only works for a few minutes then she occupies herself in other ways and gives up on the video. Her doctor has checked her out numerous times and doesn't feel there is any big concern. DOES ANYONE ELSES BABY DO THIS?