I wrote a HUGE thing on my past experiences, then realized it was me just needing to basically do some talk therapy with myself, lol.
Long story short - I can't speak for you, but my experiences with abuse left me fixated on this idea that masculinity and sexual prowess was tied to how well endowed and physically attractive/fit a person was. That led to me more or less constantly trying to compare myself to other men, which, when sexualized, led me to watching a lot of solo male porn. Not coincidentally, that stuff mirrors what happened to me.
When my cousin tried to get me to allow him to do oral or penetrative sex to me, or tried having me do those things to him, I didn't really get it. I didn't react sexually, he didn't react sexually, and so I never reenacted those things because nothing happened. I am a curious person though, so I did check out gay porn and found that it just wasn't really my cup of tea.
When my cousin coerced me to watch him get off though, that was what ended up being the most traumatic experience for me out of the 4 years total of different sexually abusive behaviors that went on. I know compared to a lot of survivors, they would probably consider themselves fortunate beyond belief if that was where things stopped, or if that's ONLY as far as their abusers went, but what can I say. That ONE time really got to me, and for years, I would occasionally watch porn that mirrored what he had me watch him do.
I do not find it much of a coincidence that after 3 years of therapy, I am not really driven to watch that stuff anymore. If I find myself wanting to or thinking about it, I usually realize it's because something triggered me to feel insecure about myself as a man or because something has made me feel like I'm not sexually desirable. Going back to one of my earlier paragraphs about how well endowed or not a person is, how physically fit, etc., watching that particular type of porn for me was a way for me to imagine myself as the person on the screen, the person who in my mind I WANTED to be so that I could finally be "better" than my cousin. Rational? Absolutely not, but I don't know many people who react rationally to being abused while they're still kids, so...
Anyways, the porn could be about many things. I've seen it suggested elsewhere, but checking out a website called "your brain on porn" may hold some interesting information for you. Weirdly enough, though it seems like a sexual orientation thing, the porn may not really be about that at all. Of course, it could be, but it's not an automatic indicator of your sexuality.
Looking at the Kinsey/Klein spectrum might also be helpful - both men theorize(d) that sexuality falls on a spectrum, with some people being exclusively heterosexual (a 0) some people exclusively gay (a 10), some people being equally split (a 5), and everybody falling somewhere in between on the spectrum.
Therapy may also be helpful - I have worked with 4 different therapists, and they helped me see that in many cases, I make a mountain out of a molehill with my sexuality because it's something I'm insecure about and it occupies a lot of my time whenever I end up thinking about it, which is coincidentally any time I happen to be under extreme stress or going into a depressive episode. It's an old fear from childhood that happens to provide a lot of distraction. I don't know if I would have figured any of that out without my therapist being able to point it out to me.