Judging from the protectiveness exhibited in the user note posted in your profile by Void, I'm going to assume that you're younger than him. Which means the earliest you could have been born is around December-January of 86-87. Which means the oldest you can be is 17 turning 18 in about 2-3 months.

So your date of birth somewhere chronologically after December of '86. Since I don't know when it is exactly, I just guess.

Your 15 and a half!