Feel like a fatty

So I am like 178lbs (ish) and I feel soooo fat 😒 I've tried diets and fail within 10days.. I tried being sick but it was difficult for me to be sick with my fingers in my mouth so that failed.. I use to not have anything except dinner and I went to 7st when I was in year8 but now I'm in year 12 I'm a heavy 12.3/7 (depending on what I've had etc.) Any tips? I'm doing at least 100 squats on a night and I'm trying now. I want to at least be 11st by August. Help? Motivation? Anyone in the same boat and wanna make a post for girls to write like journal thing??