My earliest memories go back to 4 or so. The girl my age next door was my very best friend. Playing doctor with her I learned her parts were way better than mine. We moved, I played kiddie 'sex games' with other girls my age in the new neighborhood. I chased Sandy all over the 1st grade school yard, until she very publicly put me in my place. By 3rd grade, I knew wasn't really fitting in anywhere, and just closed everybody out - but I oh-so-very-much wanted to be with the girls, I just didn't have the right whatever it was I needed - wasn't girl enough, wasn't boy enough. We moved every 2 years or so, so I had no permanency anyway, and 'loner' just became natural, and girls were just something I dreamed & masturbated about, until 10th grade high school. My first-ever-really-serious girlfriend took me under her wing and taught me to kiss. God, she was good, I learned so much about kissing from her! Sex was a year later, with a slightly older girl - I was very bad at it, despite all the how-to & fiction reading I had done - Masters & Johnson, Everything You Ever Wanted to Know, Story of O, and many many others (apparently my parents were more liberated than I thought LOL). After that, a long string - I mean, I love women, everything about them, and Ive always wanted to be them. So what better way to get as close to that desire/need as possible while still denying that's what I wanted? Not that my performance as a "penis" ever really amounted to much, but the rest was pretty good.
Maybe that's all a little TMI, but I didn't see any limitations....