Don't worry Anomie, starting at 19 as opposed to 18 is going to make very little difference if any. I think people get overly concerned with when they start HRT because it's true there is a "golden hour" to start when it can make a huge difference. However, that "golden hour" is around the age of puberty. Stopping the rush of testosterone during puberty and replacing it with estrogen has amazing results but isn't very realistic for most TS.
I have a friend from Brazil, I believe, who started HRT during puberty and honestly you couldn't clock her if you tried. The problem with that is, obviously, deciding if such a major change is right for a child so young and that's a can of worms I would never want to get into.
Try not to associate "passing and not passing" with when you start HRT. Your features are going to the same now as when you are 25 or 35 and the estrogen will have the same basic effect on you whenever you start. I've known 40 year olds who started HRT and have better results than 20 year olds. It depends on the features you start out with and the individual results from the HRT.
Once again I throw out my standard advice of.....If you haven't already, find a therapist who is experienced in gender and work with that therapist. He/she will also be very effective in finding a reputable endocrinologist that can take you as a patient.
