Jessie, hon. I have my answer and I bet you could guess if you thought real hard but good girls don't talk about pleasuring themselves in polite company (oops).
The other thing would be a chapter in a book that I first read when I was maybe 11 or 12. The book was "Many Waters" by Madeline L'Engle.
The scene that struck me was about a woman in immensely difficult labor. It was a strange thing to read during a strange time in my life. Moving from tomboyish girlhood and into hyper-hormonal adolescence. It really cemented it into my head that I was a woman. I remember reading it over and over, struggling through it with her...bonding with my understanding of self. Don't know how you're going to catalogue this but if you'd rather you could certainly chalk me up to '1st time I shaved my legs' or 'my easy bake oven'. :P
-Jo