Question about my sexuality [20M]

I'm a bit confused at the moment and would love some input on my situation.I've always been attracted to women, I love their faces, their bodies, breasts and asses, how they walk, how they talk, everything.I've never been attracted to men, nor did I in any way make advances towards men in my life. I don't have the desire or need to do so.I've been informing myself a lot about sexuality lately. I had gotten the curiosity to watch gay porn and so I did. Ten seconds into the video my dick went from limp to rock hard and I finished in 30 sec. I have no interest in men yet clearly this excited me a lot. I tried imagining gay sex (no video or images) and again finished soon.I'm really confused right now what to think of myself. Am I attracted to men? Am I not? Am I gay or am I bi while preferring women more then men?If anyone was in a same situation as me I would love some input.