hi tilgrieog
That would be cool if we think alike. Most people think I'm being ridiculous when I talk about these things

. In the few threads I've started, particularly my first one, called "Sociology of Being Gay" (or something like that), I had such a hard time explaining my ideas. They've evolved a bit since then, though.
Anyway, I've been in a sort-of similar situation as you. I went to a boy's Catholic high school, so I guess since I was also developing my sexuality at that time, I had to figure out a separation between people I was friends with and people who I was sexually attracted to, especially since just about all my friends were straight guys. Having a brother helps, I guess, because I'm definitely not attracted to him sexually and so I used that relationship as a model for how to be friends with straight guys. This can end up in unnecessary repression of sexual attraction, though.
One thing that has always helped me figure things out is to view sexual attraction separate from personal attraction. In my mind, really wanting to have sex with a person is completely separate from having a crush on that person, even if both things exist simultaneously. My anecdotal evidence for this separation is that I've known that I've had crushes on guys far before I had any desire to have sex. Since I was able to have a crush on a guy before I was sexually mature, I concluded that my crushes must be separate from my sexual attraction. That's not to say they aren't linked, or even derived from one another, but I think it's pretty clear that there's a difference between having sex with a boyfriend and having sex with a random person.
Here's some food for thought. Figure out the kinds of people who you tend to have crushes on (like your straight friend). Then figure out the kind of people who you feel (at least potentially) sexually attracted to. The intersection of these two groups is the kind of people you probably want to meet. You can disregard sex (i.e., male/female) from this grouping if that's applicable. I guess the real problem is finding those people. Unfortunately, "gay," "straight," and "bi" are not always good enough descriptors to figure out if the person is right for you. You've just got to experiment.