A forewarning, I'm gay and happily married to my partner of over a decade.
That being said, I want to offer some words of encouragement. My partner and I have been together for a long time. I came out while we were dating, which did change the dynamics. Before T sex was something that we did because we were together. I enjoyed it to a certain point, but a lot about my body and my feelings toward it affected my ability to enjoy being intimate.
Post T I do find that I feel better overall. I still have some hangups about my body. However, the feeling of confidence and security in myself has helped me greatly.
I don't think that we ever fully get away from our dysphoria. Dysphoria comes in so many shapes that we sometimes get blindsided by it, but it doesn't have to be a nail. now my dysphoria is similar to my partner's. I worry about being in shape, about being visually appealing, about how he enjoys being intimate... Those are normal worries for anyone in a relationship. I still worry about my size and how I can climax, but in the heat of things I forget to worry because I feel so positive about myself overall and I enjoy making him feel good.
My advice is this: explore. If you have a hard time being touched in a certain way or you want to know your own boundaries, explore it in a safe environment. What we did was talk. We set a romantic mood and agreed beforehand that we would just enjoy the feeling. If anything made me or him uncomfortable we would say a safe word. We had a word for stop and for pause. I learned that in certain situations, I was okay with being touched in certain ways. In others, it was a no go and I hated it. Your boundaries are yours. It's difficult to explore them with someone else, but I think that doing so can be very beneficial.
Sex for me, pre and post t is very different. But, it's mostly because of me. How I feel will not be the same for others.
You said that your partner was understanding, which is great. Sex is more than just getting off. Sex is an experience that should always be enjoyed. My advice is to talk. Whether you are pre or post t or with a new partner or an old one, never stop the communication. It may sound awkward, but it really isn't. Talking about what turns you on or what turns your partner on is very enjoyable.
If you find something that is a no go, tell your partner. Never compromise yourself and your feelings.