You know, I wrote this entire paragraph on why you're very Thief, and then I changed my mind because I saw Black Mage more. You're intelligent and not very physical, which calls to mind the mage classes immediately, and I think the trait of being strong-minded works particularly well for the Black Mage class. Some of them are very enthusiastic about what they learn and do, like Palom. Also, the entire 'I like routine with short bursts of excitement and impulse' kind of fits better with a mage lifestyle than with a thief lifestyle, IMO. They can also function well solo and as part of a team, and you said you could do either.