Good afternoon, HaleyVale!
Welcome! I would guess one of the mods will be along shortly to welcome you to Susan's and give you lots of helpful information about the site. It would be good if you could post a little about yourself on the "Introductions" thread. Go here:
https://www.susans.org/forums/index.php/board,8.0.html. . . and click on the "New Topic" button.
I understand what you're saying about a "visual focused urge to masturbate," because I experienced the same thing growing up physically male. Like you, that pretty much faded away under HRT for me, and I don't miss it. I didn't lose my sex drive, and masturbation still felt good, but the feelings were more body-focused and emotional than visual, if you can understand what I mean.
Like you, I also started out (when I was a guy) attracted to men. In high school, everybody just assumed I was just a gay guy - even though I sometimes wore girl clothes and experimented with makeup.
In the process of HRT and transition, my sexual orientation and feelings shifted a lot, and I consider myself bisexual now, though my experience with women is still (regrettably!) limited. From reading the histories of others, I gather it's not unusual for a shift like this to happen.
The main point I would want to make to you is not to feel guilty about masturbation. You're very lucky (I was, too!) to still have a functioning sex drive after several years of HRT. Some folks totally lose their sex drive during HRT. Sexual pleasure is GOOD! Masturbation is GOOD, and it harms NO ONE!
Lots of times, people struggle with the sexual feelings they have and worry about whether what they feel is what they "ought" to feel. Don't worry if you have "lesbian" dreams. There's nothing wrong with them. If you have lesbian feelings, welcome them, invite them in. And masturbation and fantasy are good ways to explore them. Like I said, it hurts no one. "Try it on for size" and see if it's something you would like to develop.