Lack of communication

My girlfriend is really on and off about communication. Whenever she’s in a bad mood or upset I always try to ask her what’s wrong rather she wants to talk about it or not. I care about her, but she rarely communicates with me and easily assumes I’m angry or upset when I really have a case of resting bitch face lmao. I told her I have the resting bitch face too. We always end up arguing, because she’ll claim she’s fine and that I’m the one with the problem when really I’m perfectly fine. I’ve tried to talk to her about us having good communication and it seems like she listens, but she never does anything about it. What do I do?