I've mentioned this in a few other threads and some guys have found it helpful. I am a gay guy who knows hundreds of gay dudes. One thing gay guys talk about when they are getting to know each other is their coming out stories. So I've heard hundreds of these. They vary a fair amount --- but never, NEVER have I heard a gay guy say that they were straight, but started watching Tranny porn and discovered that they are gay. Never. Seems to me that tranny porn is strictly a straight-guy thing.
Speaking from more personal experience, I am 100% gay, but my porn addiction got to a point where I could ONLY get turned on by watching brutal str8 porn. So, my brain was definitely mixing it up, and if there wasn't a woman being humiliated or roughed up in the video, it did nothing for me. But never for a minute did tranny porn do anything for me. Take that for what you will.
Lastly, I think that Gary Wilson is really right when he writes that if you want to understand your core sexual orientation, imagine what gender(s) you'd like to be on a date with ... holding hands, smooching romantically. If it's a guy, then you're gay. Celebrate! If it's a girl, you're straight. Celebrate! Either? Celebrate! And get on with life.