Well transition/SRS was a LONG time ago for me and even then, at 24, I was very stunted in my growth by my rotten childhood and teen years. I had no idea who I was, what I was, or what I would become.
Strangely, I never thought about "passing" - I WAS a girl. Got a problem with that? GET OVER IT! (There was no asterisk in those days, female=girl.)
The first thing that struck me was how unbelievably EASY it was to be me - no more thinking before speaking, no more having to watch how I sat or moved, no more worry about how to dress without attracting unwanted attention - I could just let it flow and it all came out right, just natural girl.
I grew up! I had the chance to find out who ME was (and she was pretty neat!) and to build a life that was all mine!
I have to say that prior to SRS/transition I had no idea, I was going through life blind. Every day that went by after, I could see more and more.