Well the best you can do is try to learn, or if she can read lips, then try to talk slow or make sure she's watching.
In terms of making her more comfortable, just repeat what you always do. if there's something she enjoys like certain activities, then recreate them each day.
I don't mean to sound condescending, but learning sign language isn't that hard, there are a lot of tutorials out there, and although they're just the basics, I'm sure she'd be happy that you're giving the attempt to communicate.
If you do try, remember that it takes time to get the hang of it, So don't stress or give up.