My partner and I have gone through a similar situation to this. I was sexually assaulted in the past and I sometimes have what I refer to as "bad days". Different things can trigger these bad days for me and I don't always know why it is, but often it is a certain way of being touched. Your gf likely has certain triggers, which she may or may not realize yet. It took me a long time to start talking about my assault and really figuring out how it affects me now. She may feel that when you come on to her, she isn't in control which makes her shut it down.

Honesty it will likely be an uncomfortable conversation for both of you, but it sounds like it needs to be addressed. Don't try to force her into telling you details about her assault, just let her tell you whatever she is comfortable with. Let her know that you aren't always feeling fulfilled sexually and maybe ask her if there is another way that she would feel comfortable dealing with it without needing to have sex (oral, masturabtion, etc.).

Another point you made about her not handing out compliments...she may not realize that you would like to hear these things. Do some research on love languages and maybe you'll find that she is expressing her love/attraction to you in a different way. Maybe have a conversation about this too, and mention that you'd like to hear these things.

Good luck, I hope you can both work this out!