I'm not conceited...right?

I used to be all fun and happy in middle school but I'm just not like that anymore. I'm in high school now and I barely talk to anyone at all. I sit and do my work and get straight A's. I dress nice. People usually think I looked pissed or something but I'm really not. When I do speak, it comes out sort of stuck up. This really loud obnoxious guy rudely demanded that I tell him how I did somethingg. And the words that came out of my mouth was "I'm smart". When people ask me for help with really simple and easy things that could be found in the book, I get a bit annoyed and have this superior tone when addressing them. My teacher asked me about how we could use the library to our advantage. I told him we could use it to photocopy stuff and he asked me if you could really do that and I said "Yeah. Well they let ME do it at least." I constantly make fun of people although I don't mean to hurt their feelings. I was just attempting to play around ... It seems people are scared to talk to me now. Judging from what I told you, do you really think I sound that mean and conceited? I sort of think I am... Sometimes I feel like I'm better than everyone else in my cles. They don't know how to shut up and pay attention and they always try to copy it off of me regardless of the fact that I don't even talk to them. So what do you guys think?