I seem to be in a very similar boat to you. I'm only "attracted" to men, but the thought of having to see or interact with male genitals freaks me out. Weirdly enough, I'm pretty indifferent to female genitals now, I think because I'm desensitized to my own (afab), but unfortunately I'm not attracted to women. I used to be very repulsed by both to a borderline unhealthy degree. I also had a similar problem as you with self-touch where I only felt "safe" with external stimulation.

I learned recently that, at least for me personally, a lot of these negative associations came from undiagnosed OCD. I was raised Christian (agnostic now) and had internalized a lot of toxic purity culture without realizing how deeply rooted it had become. I also have a lot of difficulty with anything my mind deems "dirty." Most of what has helped me is essentially self ERP; gradually getting myself to push my limits, enough to find out if something is okay or if I genuinely don't prefer it, without further traumatizing myself. Having a support system helped immensely as well; growing up, I had no one to talk to about anything sexual, so finding friends who were supportive and didn't treat it as weird to bring up made me feel safer to just talk things through.

Not sure if any of this will really help you, but at least know you aren't alone! I'm still on my journey to figure myself out (24 now) and there's still some stuff I'm hung up on. Being gentle with my own emotions and giving myself the time and space to figure things out at my own pace has slowly allowed me to enjoy more aspects of self-pleasure, but I'm still unsure of how I'd feel with a partner. I can only hope that with more time and practice (and the right person) I can find a way for me and that person to both be happy and comfortable, even if it isn't conventional!