Flat head

Since I'm going to be up all night because of LO I might as well address her flat head issue. Her back is not flat but I feel her sides are now flat. I'm not even joking, I am not liking the way her sides feel. Her side feels like a straight down wall. She's losing her curves. I know she's still a baby but are there ways to prevent this? She likes to sleep on both her sides. I know it said to switch her sleeping head positions and hold her often so she's not laying on her head.