I'm annoyed because my girlfriend pees so much
Why are you so concerned about how much she pees?
I just disgustingly can't stand it when I see her urinate.
You should stay away from the bathroom. If you know she's going to pee then give her privacy.
She is peeing at night. She is loud and it's gross.
Your gf's bathroom usage is a very minor thing and it's not right to get all worked up over. Focus on the big things in your relationship and let the little ones go.