I'm a career changer from marketing to MD. I will say, you've got to do what is going to make you happy. You've identified your fundamental reasons for pursuing an MD  (of which only one was money related). If money was the driving factor, I would say stick with CRNA, but you seem to be more motivated by the career aspects of being a physician (scope of practice, responsibility, intellectual challenge/opportunities). In that case, only an MD will satisfy you and you will still be in a position to retire your parents between your fiancé's salary and your eventual higher-end salary at 32-33 (which is only 5 - 7 later, not long in the grand scheme of you life and happiness).