My self esteem is horrible?

I'm in 7th grade and I'm 13 yrs old and omg my self esteem is so bad I just wanna hide my face from everybody!!! I am NOT seeking for attention- this is what I really do think of myself I feel so FAT AND UGLY But everybody is always like 'you're soooo pretty and your hair is gorgeous' Why can't I see that???? I never see the good parts about me anymore :( My head is just full of horrible stuff that I can't get rid of and its killing me