I amm So Lost & Dont know what to do. Please Help?

So lately I been feeling so sad and mad all the time at myself because i dont feel pretty enough or because i feel like no one understands me. i am a nice girl i guess, i think before i speak, i barely curse, i dont disrespect my family or teachers, im not the type to party and i like doing things the right way. i like helping others and i feel like this is destroying me. i hate being so nice and right all the time, it gets tiring and it feels like nice people never get far or what they want in life. nothing feels right. the things i try to do in like 2 years, My bestfriend gets it in like 2 days -___- & it gets me so mad, any advice on what i should do ?! & Thanks