It's just something I always knew. It goes as far back as preschool when I had a tantrum about a gendered art project to being the dad for "house" all the way to when I was eight years old and not only unintentionally discovered what packing was (or feeling right in my skin when I wore boy underwear for the first time) but found myself in an intense state of panic when a truth or dare question came up regarding something deep and hidden--having me scared about opening up to kids I went to school with about something I felt like I was the only one going through with, and coming from a family that pretty much ignored me; there was no way they'd understand. I don't know if it was a blessing or curse that I was quiet about it (despite my family saying they "always knew") since they brushed me off when it came to bullying or feeling like something was deeply wrong, which ended up with me being diagnosed with many mental disorders at 16.
I was always envious of my male friends and I felt awkward at slumber parties, school functions or anything that's typically "gendered". A few memories that are rushing back to me are from when I was under the age of 10.
(1) When I was in daycare (pre-K to kindergarten), I was saddened that I couldn't build birdhouses with some of the guys or older kids. I don't know why I got do bummed about it, but I did.
(2) It wasn't a big deal, but it involved the colors we had at our kindergarten graduation. I don't know if this is me now getting weird about it or it was when I was a kid; but it was about how I had to wear white and my male classmates and peers had red.
(3) The typical issue many trans kids had, which was wishing on stars and birthday candles to wake up "normal" and getting depressed about it just being a pipe dream in the morning. Honestly, this went on until I was in my teens.
(4) Something happened with a friend when we were like seven or eight. I'll just say the pants were off and then I got the big picture as to what made us different and it was fairly traumatic and got me depressed for a long while.
(5) I don't know if I was nine or this was later on, but I found an old copy of the Guiness Book of World Records that mentioned a surgeon in Colorado who specialized in SRS; and then and there I knew that's what I wanted more than anything. I didn't feel so alone for once. I had a silly, childish view of how it all went down; but I'm sure people would say it was cute. It's been 12 years, and nothing has changed for this queer boy.
So yeah, I pretty much always knew--even though I spent a good amount of time in my preteen-teen years battling with my feelings and was in a struggle to keep the buried, even when they tried clawing to the surface.