Passing is such an interesting thing. I have a friend and she has really lost in the genetic lottery. Her shoulders are wide as a brick house, her torso is shaped like a V, she has no hips, she sprouts facial hair and her voice is as gravely and deep as any truck drivers'. And!!!!! she is a a genetic female. She never gets mistaken for a man, ever. In fact she exudes femaleness.
We tend to think of passing as a perfection of a ruse. All of the discussion here revolve around that aspect. Facial surgery, behavior, clothing, comportment, movement etc. are all perfected to make the world believe that we are who we are. Yet, there are websites now that teach people "how to spot the tranny". For instance here or here.
No one ever seems to think that being female is really not about creating an impression, succeeding in a ruse, making people believe. The friend I mentioned above would hardly have passed any of the "spot the tranny" tests but she is unquestionably female and is witnessed and mirrored as such. In passing that is your measure of success.