I was looking less for concrete answers (what is it like to transition) and more about what your experience was like (what was your experience transitioning), since it's not something I can ever understand on a personal level, not being transgendered myself. Therefore your answers were completely helpful.
I think it's interesting that you discuss how consciously you tried to learn and adopt female mannerisms - that's not even something that comes naturally to all women! My body language is often "off" when I'm in a group of nothing but women, I believe as a result of usually dressing in an almost masculine fashion and having some masculine habits and mannerisms. I was always a tomboy and spent much of my young adult life around men in male dominated professions (military and law enforcement). Although I am not a lesbian, I have been mistaken for one before, but as you alluded to, this is just who I am - a kind of masculine straight female, and sometimes that causes others to make snap judgements about me that are incorrect. Getting comfortable with yourself, which it sounds like you are, can be a challenge but is ultimately so much healthier.
FWIW, my post about the DSM-IV diagnoses was not intended to state that you personally have any clinical diagnosis, only that transgender is completely different from cross-dressing. There's a lot of debate even in the mental health field about the necessity of even having codes and labels for mental issues (to say nothing of the potential stereotyping of the "mentally ill"). That said, as the DSM-IV currently stands, most transgendered individuals would probably qualify for a diagnosis of GID at some point in their lives (most commonly in the pre-transition stage) simply due to the fact that they are transgendered, and almost certainly experience some distress because of it as a child/adolescent/adult. That distress will hopefully become minimized as society becomes more accepting of the concept that gender identity is not a binary, all or nothing dichotomy, so that transgendered youth can simply be accepted as such and be allowed to transition prior to puberty with a minimum of distress and societal rejection/bigotry.
Finally, I also respect the privacy of your partner, and I'm glad you have such a supportive person in your life.
Thanks for your willingness to answer some questions.