Thank you both very sincerely for your interest, but I can't imagine what else I could do. I've been to two therapists already. And then there's the fact that I very much do not want to accept sexuality. I've been at odds with it my whole life, it's a part of who I am. Sure I wish more than anything that I didn't always feel like I'm constantly waging war on myself, but I've been looking for solutions for years and found next to nothing. I think I'm just going to have to be struggling for the foreseeable future. I know that's not the best outlook, but hey, there it is.

Which lands me in the quandary of having to turn down advances from women. Heck I've had to give one or two boys the cold shoulder before.
Let me give my most recent example to kind of illustrate my point:
When I was on a cross-country hike, I spent one night in the company of a group of college kids out for an evening of casual camping. I got along great with them and they invited me to come hang out by their fire and have a few drinks. I happily obliged.
But there was this one girl with them who was showing my "warning signs" of getting just noticeably too friendly with me. I shrugged it off. Somehow I ended up sitting next to her by the fire, she has a few drinks, and before I know it, she's all snuggled up against me and all but groping my side while the rest of the group is happily singing campfire songs. I am, naturally, freaked out. I have no idea what to do. So I just kind of brushed her off of me, announced that I had a big day of hiking to do tomorrow, and headed back to my own camp. I saw her again the next morning and she kept apologizing for anything she might have done to offend me. I responded to all of her concerns with a smile and a reassurance that it was "No big deal."
But to me, it had very much been a big deal. This girl could not have been clearer with her intentions and I had no clue what to say to politely turn her down without being kind of a jerk, kind of a killjoy, or more than kind of awkward. All the other people there just seemed to kind of, I don't know, except what was happening. It weirded me out because of how completely off-the-table the potential situation was for me personally, versus how normal the concept seems to be for most everyone else my age.

These are the kinds of situations I'm worried are going to crop up here and there. As StrongerMan said, honestly is of course the best policy. But I'm still feeling out of my league here.

A big thank you to everybody who has taken the time to respond so far, much appreciated!