Mmm, I remember first discovering the difference in genitalia very early at preschool... the bathrooms had been unisex (we were too young to matter, I guess?) and rather open, almost communal. I didn't really understand any meaningful difference for a long time though. Other than the fact that I rarely if ever 'fit in'.
I really remember very little in the way of details of my childhood (already!), but my story is a lot like Julie's. I think it was sometime during middle school when really I started to wish and pray that I'd be physically transformed. I just knew there was something not right, that it would be 'better' if I was transformed, but I couldn't understand what it really meant at that point. Especially before I went to sleep and after I woke up, I begged to the higher powers, and every morning, I woke up wondering if it worked, but quickly realized there was something still between my legs.
But at that point, I never really thought to question why I wanted it. I hadn't even considered that I could possibly be a girl 'inside'. Not knowing that there was any difference between sex and gender, I came to believe that I was just having strange and perverted desires. So I fooled myself into thinking that I just "want to know what it is like", and there was nothing 'wrong' with me.
So I guess I didn't really start questioning my gender identity until Jr High/High School, around when I first heard of a 'sex change' probably somewhere on TV. (I... think it might have been Springer. >.< ) But even after starting to wonder, I didn't really seriously consider that it could apply to me (I was terrified of the idea. I wanted so badly to be "normal") until a couple years later. So I didn't "identify" until midway through high school, when a little bit of research "woke me up" to what I already knew and made me realize my endless recurring feelings weren't just some fantastical perversion. I checked off 8-14 though, because that's when I feel like I realized inside. It just, unfortunately, took a while for me to stop being afraid to accept it (though I still regress from time to time =/ ).
~Kaitlyn