In constant doubt over sexual orientation, possibly bi?

I was in the same situation. I think you should stop beating yourself up over your bicuriousities. I also think the key to figuring out your sexuality is experimenting (assuming you are not in a committed relationship.) Date a gay man, fool around with a "straight guy" and have some relationships and sex with women. You may find out that it's just a fantasy. You can't possibly decide how to live your life from your porn preferences. I know that I had a great time sexually with men but just could not emotionally connect with them enough to have a long term relationship.