@ Emily - It is, thank you!
We've talked a little bit about it, but not a ton, mostly about who should be the one to tell my parents (who we'll be living in the same city as) and what sort of language he likes to use. I don't want to say it hasn't been relevant, just that it hasn't really changed a lot about our relationship - she's the same person as always, and I love her as much as ever, and for as many things that have changed (like pronouns), others have stayed the same (like her preferring "girlfriend"). Overall, I would say I feel really positive about it. But I do think it's worth bringing up again, now that you mention it. One thing I could talk about is that in the past, it's been important to her/us that we read as girlfriends. After working out my own identity I'm no longer invested in this (it's not accurate anymore from my end, but nobody is going to see us on the street and assume my correct identity, so whatever misinterpretation is easiest and makes her happiest is good enough for me), but it would be worth it to talk about how that might change with her transition.
Upon reflecting on it, I honestly think there's two reasons. The first is that I don't like any comments being made about my appearance, positive or otherwise, so it's really hard for me to remember to compliment my girlfriend physically too. I already get nervous complimenting his outfit or appearance because all compliments make me uncomfortable and it makes giving compliments really uncomfortable too because I have trouble getting out of that mindset regarding other people. So I think part of my concern is that if I find his appearance very cute and attractive right now and I already struggle to compliment him properly, I'll get even worse at it if there's an element I'm not personally into.
The second is that I do really bad with changes. Your comment about "It’s also possible you will grow more comfortable over time as his beard grows after starting T" and comparing it to actors/characters made me realize that a lot of my discomfort comes from imagining someone who is currently completely bare-faced with a full beard, lol. My dad has a beard and so do a couple of my favorite characters - all people I'm not into, but all people I feel really weird imagining clean shaven. So it's likely I'm sort of neutrally not into beards and the discomfort comes from imagining a sudden physical change. So maybe it's possible that the gradual nature of the change - especially since we'll be living together when he's on T - will help me ease into it a lot better!