I think my girlfriend is amazing except...
Except for what?
Her level of attitude is a problem.
It's not wise to accuse your girlfriend of having an attitude problem. She might get mad to hear you speak  of her in this manner
I can't fix her attitude problem though.
Sometimes people have flaws but how we care and love them despite those flaws is what matters. She might not intentionally want to get upset so often and its good to be there for her when she does to calm her down. I'm sure she'd appreciate you even more if you did.