Hi Alice! If you harm yourself the only thing you will achieve is making your body suffer. You may not realize it, but hurting yourself is not an option to be prettier. God left you on this world just the way you are, and in His eyes you are a beautiful person. The feeling that you get when you harm your cheeks is not happiness it's just pain. You are in deep pain Alice, like Rev. You are too harsh with your image.
Always say to yourself that you are one of a kind and unique girl, pretty just the way you are. Be more confident!
I also had problems with my image, i considered myself ugly, couldn't find a boyfriend...i was unhappy...but never turned against myself. I started to ignore everyone who had a problem with me because i knew that if i hurt myself they will make fun of me more and more. Imagine the happiness in their eyes if they ever found out that i turned against me. Just try to be surrounded by good people, who like and love you...step by step your uncertainty and the need to hurt your body will disappear.
:) You are a great girl, do not ruin what you where blessed with, an unique soul.