Why can't i get drunk?

I drank 12 bottles of corona. With lime, of course. :) as well as a 26oz of rum straight from the bottle; I can't feel a thing. When I first started drinking it usually took a good 10-15oz of hard liquor to have an effect, but now I can drink until I physically cannot drink any more without feeling a thing... I'm also 16. This really perplexes me.