as an adult male, I do believe that excess masturbation can inhibit you from climaxing during intercourse. the "feel" of your hand is significantly different than that of a lubricated vagina and you have more control on the "grip"
I also second Teko's advice...you're awful young to be playing adult "games" and I hope you a properly prepared for the consequences. Intercourse has been known to produce babies.
Jim
The first thing I would say to you at your age is that guys of your age are number one, inexperienced at best. Secondly, if you are being pleased by yourself and not the other partner, it tells me that your partner is not rising to the occasion and is more often than not concerned with their own release and not yours. You body is still maturing sexually and so is your mind. And same with the males at this age. Just keep in mind that when you play adult games, you have to also be ready for adult consequences of your actions, and at the very least, use protection.
Maybe we'll get some males to help ya out here. When you say you feel it does . . . well, does it? I couldn't tell if this is actually occuring or if you just think it will occur. Masterbation is not mandatory. If you don't want to do it . . . you don't have to. good luck