I dont think i can but i know dat i can ..all i need is..?

hey guys am in a big confusion...i wanted to do medicine m my childhood but sumhow i drifted away n now am doin bsc..but i am not happy inspite of havin met gr8 frends..der r reasons dis... my cousins r pretty well in der studies n ppl compare me to dem..n now am sure i wanna do medicine..not just to prove 2 ppl but also for my happiness.... still no one s der dat believs in me n hu can say dat i can do it...i feel so low...any help..??