this is probably an old post
but I too am mentally ill so i hear ya.
Schizophrenia here...
i have a tendency to sound pretentious when I talk about music theory some times so I get that but I usually stop that pretty quick by throwing in a joke. Only reason I sound pretentious to begin with is when i get into the advanced music theory where there might be crazy terms like sub-dominant minor modal interchange so it's not on purpose, but people usually figure out pretty quick that I'm not like that since I'm open to learning and sharing information with anyone from any level. and that's the way to be

With your case, I guess the best thing to do would be to find an even medium?
sort of a humbled quiet confidence? I dunno..
I also wouldn't worry so much about what people think this much.
It's good to be aware of how you come across to people but in general
Just be yourself
