This is to be expected since for a given depth change, the pressure -- and therefore your buoyancy -- changes more rapidly when shallow. The further behind you are in noticing & reacting, the worse the you will yoyo. You will improve with practice. (Fixing your trim also helps with this issue since it is easier to keep a consistent depth.)At 8-9m plus, it was easier to control my buoyancy. I yo-yoed a lot less