I'm happy to have found this thread, and I'm sorry to bump it by responding years after the last reply... but if it's relevant to me, then it might be relevant to somebody else out there, too, and isn't that the whole point of this site?
Just recently, I've begun to come to the realization that I might be somewhere on the "Ace" spectrum. It feels embarrassing to be my age and still figuring out my sexuality (or lack thereof), but I suppose it's better late than never.
My only real turn-on is medfet. While I recognize when someone is attractive, I don't feel the urge or desire to have sex with that person. Yes, I masturbate, but when I do, I have never fantasized about having sex with someone - instead, I always imagine a medical scene: i.e., examining a patient, myself being examined, or witnessing an exam. Even when I seek out "spicy" material online, straight up intercourse (m/f, f/f, or m/m) doesn't do it for me. I would be open to a romantic relationship if I were to meet the right person, but searching for that person has never been a priority for me.
I always just thought I was weird, and maybe I am, but it's comforting to know that there might be others like me out there.