For years I did not know I was transgender, never had even heard the term until a few years ago. I just knew I was different. My desires didn't match who I was suppose to be. I wanted to wear things girls got to wear. But didn't think that made me a girl.
When puberty hit, my sexual preferences seemed to line up correctly, I was attracted to girls. This helped to re-enforce that I was not a girl, after all girls did not like girls. (this was a bit before LGBT was common knowledge, at least in small town East Texas)
My desires never went away. I would dream up scenarios that put me in women's clothes. Elaborate fantasies- witness protection program where I had to be disguised for my own protection - government spy, my cover was as a woman. There were more, always in my thoughts. I can not think of a time when the scenarios were not running in my head, reasons I should be presenting as female.
Eventually I learned about transgender, and I learned that your gender identity had nothing to do with your sexual orientation. I began dressing in public, and it was amazing. But like an addictive drug I needed it more and more, until just dressing seemed shallow. I felt that I was just pretending, playing at a role.
I wanted it on the inside, not just something I put on the outside. After discussions with my wife, I started HRT, to make my insides feel more aligned.
And now, I feel right, I feel like me.
That's How I know.