I feel fat

I'm 21, my height is 5'8" and i weigh 175lbs . I feel fat most of the time and I think everyone around me lies and says that I'm not fat just to make me feel better. I hate it and I wish I could just lose the weight. But I've tried almost everything from exercise to strict diets and I don't know if I'm not doing it right but it doesn't work. I cry about it and it makes me depressed. Any words of advice would be helpful. Thanks.