Welcome to Basenotes!
I go to an all-boys school too (I'm 17 atm), though we are co-ed in the sixth form. Anyway, here are some recommendations:
Dior - Eau Sauvage
I haven't tried this, but it is a really popular (and liked) fragrance here at BN. It's a citrus fragrance, and suppose to be quite masculine and elegant. Sorry, that's all I know about this one (will try it in the future)!
Paul Smith Story
I have this, and it's also a citrus fragrance. It has notes of grapefruit and vetiver. I think it might be suitable for you as it's reasonably priced and IMO, isn't a "loud" fragrance. Noone would be attracted by it or offended by it. It smells great too.
Burberry London for Men
A fragrance with boozy accords. Really nice and probably won't offend/attract others. It might be a bit heavy for summer/warm weather wear though.
Lolita Lempicka au Masculin
I guess this is quite a "sexy" fragrance and probably quite unique compared to other fragrances. It has notes of anise and vanilla. Definitely worth trying and suitable for social gatherings (though use it sparingly!)
A gourmand fragrance with strong notes of chocolate and vanilla. I guess it's similar to LLaM in a way, but different. It's pretty long lasting and projects well, so girls may find it sexy and whatnot.
Hope that helps, though I'm not very knowledgable (yet)!