I agree with the folks who said "go for it." My dx is cyclothymia, which is not as severe as bp. I have struggled a lot in my life, however I always did well in school and have a master's degree. I do have student loans, but my income is 3 times what I made with just my BA. BA in English, not very lucrative.

I wanted to add that I think it might be easier to go ahead and go for the master's in psychology, rather than changing your mind later and trying to switch careers. Once you're out in the work world and have your life and home set up, might be more difficult to disrupt that. I stole this from somewhere but I can't remember where: once you're in a career, you're in the golden handcuffs. You're paying for your home, car, maybe raising kids. You'll have a lot more expenses than you do now and be accustomed to your lifestyle. It is definitely possible to go back later and switch careers, I just think it is easier to start out in the one you want.

Best of luck!!