Well, at one point I realized I wasn't comfortable at all with being female and found myself feeling like I was male.. just with the wrong body parts. Everyone experiences it a bit different though.
I always felt like something was off with my body as a kid. That and I was told "no, that's for girls" at almost everything I wanted to do. When puberty hit I felt horrible and disgusting; like everything about it was completely wrong for me. Everyone told me I would "grow into things" and to just accept it. Problem was the more my body changed towards being a guy the worse I felt. After many more years of misery and trying to believe others I finally caved in an accepted I was a girl.
It was very gradual for me. A year ago or so I had a "Holy shit, it all means I'm a transgender man!" moment, but in reality I knew since early puberty that I'm more like a boy than a girl. I knew I had the mind of a guy and body of a girl, but thought it's meaningless, and for some time, I identified in an agender-ish way, and questioned my gender over and over again, experimented with gender expression, grew up to be a very masculine person against all odds, and last year it started to make a whole.
That is a long story my friend. These days I can look back and clearly see signs from when I was a kid but as a kid I didn't know. As a teen (13-17) I had strong dysphoric feelings but started repressing them because I was often told on LGBT sites that I was faking them because I didn't fit the typical trans experience. I always had a slight jealously towards trans men. I envy them for being trend and for being able to become male, meanwhile I was just a female that hated being female and having a female body and having my relationships viewed as straight. I was 22 and at an anime convention when I really started thinking about it. I remember thinking about how much I hated that no one would even think ibwas a guy for a minute. It was something I thought about that whole night, thinking of past events, and of repressed feelings and ones that never went away. By morning I had the thought of "is it possible that I might be trans? Is it just wishful thinking?" I started researching and talking to my best friend about it. I started imaging a life where I wad male and not female. The simple thought that I could be male in the future seemed to make life worth living. I had lived life sort of numb and shifting to fit the wants of the people around me, but the thought of a male future made me want to actually plan it life and do something with my future. That I could be someone's boyfriend or husband one day made key tear up because it was something I had secretly dreamed about. Even after all that it took a good 4 to 6 months for me to be sure enough to talk to other trans people. I was just laying in bed and watching the rays of sun against the wall and thought "There is a strong chance that I am trans" and I didn't feel fear or was overjoyed. I simply thought "So what will I do now?" And that is when I joined this site. To talk to others, to see if what I feel was valid, if being attracted to men and being slightly feminine still meant I was valid. I was uncertain for months and months. It is only recently that I felt the level of certainty that I wished I had back then. I still have moments of doubt, I probably will even after I start T. I think that is normal of all trans people
for me it was sort of an evolution, i came out as Bi, and soon after i recognized that there is a strong female component to my soul and identified as Bi Gender, i still do. the evolution came with the help of my therapist in that the female part of me is the strongest and i've started to medically transition.