She sounds like someone I knew at Gallaudet when I was doing interpreter training. NF2, lost her hearing as a very young adult, and wanted to learn ASL, because she was already blind in one eye, and was concerned about the possibility of becoming completely deaf-blind. She also needed the support at Gally to get through college. She’d tried a hearing school, and even with note-takers and tutors, she couldn’t handle the large lecture halls, and the fact that the school didn’t really seem to want her.
At Gally, she was visually impaired, and a new signer, but her deafness was irrelevant, plus, Gally doesn’t have any big lecture halls.
She spoke pretty well, even though she hadn’t had much speech therapy since losing her hearing. She might have a CI by now, because she’s exactly the kind of person CIs were meant for-- people who became deaf as adults, and had brains that “knew” how to hear.
She was very outgoing, and wouldn’t hesitate to let people know-- in the nicest way-- when something wasn’t working; if she couldn’t see, wasn’t following signing, wasn’t lip-reading a person well.
I have never dated anyone Deaf and blind, but I have several Deaf-blind friends, so I think I can address this. Just take her lead, and use whatever communication system works for her. If she talks to you, listen, but don’t hesitate to ask her to repeat something you didn’t understand-- don’t pretend you heard something clearly because you don’t want to embarrass her. If she signs, take a class. Ask her if signing and talking at the same time is a distraction, or if the dual input helps. She may ask you to pick one over the other-- speaking in quiet places where the light is good (for lip-reading), but signing when there is background noise.
Be prepared for other people’s reaction. People are going to think you are taking care of her-- that you are her attendant. You’ll sometimes get just one menu in a restaurant. Be prepared to keep reinforcing with people that she is independent, and you are there for the pleasure of her company, not to help her. If you have regular hang-outs, and other people you hang-out with, they’ll catch on, eventually.
Now, there’s nothing wrong with occasionally interpreting something for her, but you want to avoid people making the assumption that that’s your job. Believe me, this gets really old, fast. You might feel like yelling at the 300,000th waitress who asks, in front of her “What will she have?” and believe me, people’s jaws will hit the floor when she picks up the check.
Mostly, though, you get into a rhythm of whatever works for you, and you will stop thinking about what she can’t do, and just think about the things you two have fun doing together.