Why am i so insecure?

Okay well im 14 years old, im a girl, im african american. . And i weigh about 175 or over (which isnt good to me) my mom says im beautiful and all myfamily ad friends say that too but their suppose to say stuff like that so idont believe them . I wanna wear make up but my mom doesnt allow me she says i dont need it . I wanna lose weight but icant stay commited. Im starting highschool august 1st and i wanna be pretty to people especially guys. Help? Any encouragemet things? Lol i dont know but help please