How do I maintain fullness in buttocks and decrease swelling in abdomen?

I am 4 weeks post op. My butt has shrunk a lot, I am not sure if its the compression garment I am wearing that may have the butt area too tight. Is there a way I can maintain the fullness or do some glute exercises to make it appear bigger? Also my abdomen is extremely stiff and the skin has gotten dark. I want my waist to look slimmer. Should I change my diet to lose inches around my waist? I do not want to lose the fat left on my butt. Any tips to maintain fullness and reduce swelling helps.