Umm i need a little girl help?

ok i guess you would call me obese but it doesnt realy show. im 14 and 1/2 and 235 while being bout 5' 10" or around there. i kind of think that girls like being made fun of because i sit next to someone and made fun of her with the way she was looking through the microscope near the beginning of the year and were ok friends. but i have a girl in my other cl who i offer to take back her book for her, give her gum or the seat next to me to rest her feet on and she doesn't even bother talking to me. im so confused! im more of the kind of guy where im funny if you understand my kind of humor. also i hang out with some of the kids who drink do drugs and smoke and so on and now they all think i do it and i don't i used to drink but now i've stopped and i feel much better. how can i convince them that im clean! sry like three questions in one plz answer these!