too much attraction? what is wrong with me?

I am 16 and in year 11 at school.

ill be brief.

I have had many crushes on girls over the years but none like this one. I cant stop thinking about her and she turns me on more than i thought possible.

I realise my infatuation is most likely based on physical attraction but the thing is she stands out so much from all the others. There are girls at my school which any guy would give his right testicle to sleep with once, yet i am barely attracted to any of them. Whenever i see this other girl however my knees buckle and my downstairs region has to be mentally restrained.

is this normal? why am i so infatuated with this girl i hardly know. she makes me dizzy every time i see her. is it genetic or what. i have no idea.

help