Anon,
I would stop freaking out and let your impulses lead you where they may. As complex organisms, the biological, psychological and physical aspects of our being develop at their own pace and in their own individual manner. You may be experiencing a homoerotic strain of your psyche that remained repressed or never resolved itself in your early teen years and is only making itself evident now. It doesn't mean you're gay, just acting out some long dormant impulse. Or you could be realizing something fundamental about yourself that will have long term effects on your relationships. Sex is a powerful component of the human experience and pornography a handy (and safe) way of exploring various aspects of its "sexpression."
You might want to ask yourself this: do you IDENTIFY with or DESIRE the perfomers in their hyper-masculine behavior? If you're able to answer this question honestly, you might have a better handle about the experience you are undergoing. The former would suggest that you are seeking models of masculine self-esteem--not so much homosexual as homoerotic. If your focus is more about the actual possession of men and their bodies, you might be legimately bi- or homo-sexual. But rather than labeling delicate and subtle actions of the heart, I would urge you to cut yourself some slack and enjoy your experimentation with a healthy dose of self-awareness. At the same time, might I suggest you also supplement your private indulgences with some legitimate socializing, male and/or female, so you don't compartmentalize your feelings but rather give them free reign in the full expression of your being.
You only have one life--live it to the full!