It could also be that the "mechanical feel" of sex was more about the actual sex... If that doesn't make sense, bear with me.

This far, you have only had sex with prostitutes. I will leave my own views on prostitution out of this post as they would not be in any way constructive to you, so that's a debate we should take elsewhere. But, your sexual experience is, therefore, masturbation and self-release (mostly by visual stimulation like porn) and going to prostitutes.

Maybe the problem is what kind of sex you've had. You've had sex that's just sex, just the "mechanics" of it, just release-driven. Sex is an instinct and release is a chemical reaction, sure, but sex is more. Personally, I didn't really start enjoying sex before it became intimate. I had casual sex for almost two years after losing my virginity and I was good, sure, I got the sexual release I wanted, no strings attached, etc. I was on to my friends about how it was great and being single was perfect.

Since I first had sex with someone that was about MORE than just a release, just an orgasm, I never looked back. I thought people were overreacting, trying to sell the cultural concept of monogamy or "sex with feelings" or at least with some sort of interest. But oh my, it's so much better. Sex feels better when you're with a partner who doesn't necessarily care about you, but who see you as more than a tool to get a release. Someone who explores your body, who is creative, who enjoys sex not just in terms of release. Someone who turns you on and interests you.

To put this now rather long post shortly: You have only had impersonal sex. It's not so weird, as you've had complexes, but it might explain why you don't want sex that much. You can get the release on your own. But to truly feel sexually fulfilled, and to get your sex drive working properly, the best method is to stop thinking about sex as just something you do that leads to orgasm and start thinking of sex as a way to get to know another person on a whole new level, as a way to get your body to experience stuff like you never imagined. Not necessarily a girlfriend or someone you want to get serious with, but it has to be someone you feel a connection and a spark with. It could be a friend, a collegue, someone you've just talked to a couple of times who you like. Then it becomes something else than sex with a prostitute, for them it's a job and their goal is to get you to come, it's what gives them money. Sex is not just a "technical" thing, and that might be the issue for you.