How do I tell a girl I like her?

I'm 15, she's 14

I'm a virgin, she's not

I'm not really the type she goes for as she goes for the more asshole type. I'd like to think i'm a sweet guy. She usually is attracted to the more muscular and physically fit type of guys. I, on the other hand, am not all that fit, but I'm not obese either. I'm about 140lbs and 6ft tall. I have long blackish brown hair that I straighten to go for that more scene kid sort of look. I am not sure if she likes me but from what I've heard I am a sweet, charming, polite guy. I'm best friends with her brother but in the event of dating her would not sever my friendship with him. When I'm around her I'm usually a bit awkward when it comes to trying to start a conversation with her, because I don't know how to start one so I rarely have anything interesting to say therefore I'm most usually quiet. I've known her for about 2 years. I reallly like this girl and I don't intend on dating her just for sexual gratification like most of the other guys she's been with does. I am narcoleptic and cataplectic (though, I don't talk about it much nor is it embarrassingly noticable) which leaves me in a bit of an uncomfortable situation since she knows of my medical condition. I don't have a car nor am I allowed to leave my house on school nights. I admit, when I'm in relationships I typically like having a clingy girlfriend because then I wouldn't have to usually worry about them leaving me. But she doesn't seem like the clingy girlfriend type. I don't smoke weed or do other drugs unlike most of the other "popular" kids at our school. From what I've heard from my past girlfriends, I'm a sensative guy and I myself can be a bit clingy. I don't know if she's into that type of thing or not. I'm not very unique other than the fact that I play guitar

I've tried asking her best friend for adice on this subject but I don't think her friend has talked to her about this. I've known her and her brother for 2 years and we've became friends over that period of time. I started developing a crush on her during mid spring 2010, but I've had other relationships since then.

I don't have anything else to turn 2 sadly and I don't know what her reaction would be if I did confess to her. I text her on the phone usually every day but she usually quits responding to me within a conversation thread of 3-4 messages from her.

I really like this girl and I'm ready to do just about whatever it takes and I want a intimate relationship with her (emotional and/or physical) with her. I'm open to criticism so anyone whose willing to respond to this long question, I will take their advice. However I will not accept the answer "maybe she's just not in to you and you need to move on" or anything similiar.

Thank you and please answer as soon as possible.