I'm really jealous of my sister?

Hi i'm 16 years old girl and my sister is 21 , i've always been jealous of her even when we were children , I've always felt that people in general preferred her on me people used to think that i'm evil & sly ,, especially my mom , anyway this is why I'm jealous of her right now : 1- she's prettier than me , she has a straight perfect nose & a perfect body while I have a nose like a goblin & I have a curved back , anyway i don't care about the looks too much , 2- she's not miserable like me , she used to get high marks at school for example 95% & now she's studying architecture , while I'M FAILING AT SCHOOL , I suck at school that I had to go to summer school , because i'm just a lazy asshole , 3- she can play the guitar really good , & I've always wished I can play the guitar it's like my dream but I just can't learn it , whenever I start learning I just realize how lame I am & that i'll never be able to play it , you can say i'm the type of people who lose hope fast , I'm not trying to be mean here , I mean I love her to death & I don't know what to do if she didn't exist , but I'm just so jealous of her , please don't say "just accept your self " & stuff like that , because I'm really miserable & I need to change but I don't know how . sorry for my bad english .