When I think about some music theory, I always think in C major. It works but it's slow because I have to mentally transpose stuff into Cmaj in order to make sense of it. How do I get away from it and become more fluent in other keys mentally?
i was in the same situation and i just started trancribing chord charts to every recorded song i own. after 30 or 40 songs i really started to get comfortable with all keys