First, don't stress too much about your age. Many, many teenagers watch porn; you're more likely to get in trouble for downloading music, to my knowledge (meaning it's pretty darn safe). Secondly, while I do understand not wanting your parents to know, watching porn isn't something to be ashamed of. Sex and sexuality are both natural and healthy; it sounds like you just have an unusually high sex drive. Honestly, I can relate.
It's not a bad thing, and personally I'm quite glad to be the way I am in that regard.
Just don't go getting viruses on your computer!
The atoms that make up you and me were born in the hearts of suns many times greater than ours, and in time our atoms will once again reside amongst the stars. Life is but an idle dalliance of the cosmos, frail, and soon forgotten. We have been set adrift in an ocean whose tides we are only beginning to comprehend and with that maturity has come the realization that we are, at least for now, alone. In that loneliness, it falls to us to shine as brightly as the stars from which we came.