For the first 6-9 months on HRT, my sex drive completely disappeared. I remember that I could look straight at a woman's chest, and feel absolutely nothing. For some reason, my sex drive started to come back at bit somewhere at the 6-9 month mark. It seems to rise and fall. One day I'll really notice it, and then it's gone for another week.
To the extent that I do experience a sex drive now, it's not the same as it was before I was on HRT. Before HRT, it was like a little kid demanding candy. It just WANTED it, and it wasn't gonna shut up no matter how sick of hearing about it I was. Now, it's easy for me to dismiss it. I might see a picture on Facebook or something, and feel slightly aroused, but I usually feel little or no desire to actually act on that arousal. Even when I do, it's easy for me to just decide I don't feel like it, and it will go away quickly.
I also notice that increasingly, my sex drive acts right along other feelings. Like, I might feel a desire to look at a woman's chest, but the sexual part of that is weaker than whatever jealousy I'm feeling that she has bigger boobs than I do. I might be simultaneously feeling some slight sexual arousal, and thinking a lot about how her body differs from mine because I'm trans. I might even be thinking a lot about how I like her as a person, or what I admire about her. It's never like it used to be, where once I felt aroused, that was all there was. It's more of a quiet reminder that I'm a little bit attracted to that person.
I also very rarely actually feel the things I used to feel when I was aroused. My arousal now tends to be more of a subtle, whole body or mental thing, where it used to be like a fire in my groin. I actually very rarely even experience sensation in that area anymore when I feel what I'd call arousal now. It's more of a mental shift in attention than any physical sensation.
I don't experience much in the way of sexual thoughts anymore, either. I might notice the way a woman looks, but that's the end of it. There are no intrusive thoughts or anything I have to try to ignore. I don't really think of women sexually anymore so much as I just notice things about them that I'm kind of jealous of.