Please help. junior in high school lack of friends. dont know what to do anymore?

i am a high school student in the 11th grade.... i lost many friends slowly since the 5th grade.... i have some friends who i speak to online and maybe i speak to 5 of them in school but usually barely hang out maybe once in 3 months... and i also have this one "friend" who i suppovely bumped into this spring break in florida, and we chilled and went to a movie together for two nights in a row. now when we get back to new york its like he doesnt even know me, but usually i instant message him on Aol instant messenger. So i have a friend problem,and i really dont want to switch schools because high school is almost over.. I really wnat to change and show people that i am a good person, but in my school there are two types of [cliques] and i feel like i will never get into them, and never will. On facebook there are pictures that my so to speak "friends" have and they are with everyone in our school and i look and i am really jealous how i am not invited to any of these gathers which is usually every saturday, and then i feel like crying. I really dont even like going into school groups or sports because it takes up too much time after school and then i cant concentrate on my studies and i am not doing so well in one of my main subjects. I serouisly am sick of life and I sit home on saturdays and my parents always ask me why i dont go out with my "friends" and i ask my friends to go out some saturadys but they usually have an excuse. please help me, im not a nerd im an average good-looking kid in high school and when i look also at people or my "friends" i roll my eyes because they think they are superior and better which [they are]. please help me how can i fix this????