For along as I can remember I never really felt I fit in with the other boys in my classes, even when I was in primary school. I was never flamboyant but I just didn't really gel with what I was 'supposed' to be doing. However, I never really fit in with the girls in my classes either :P. Anyway I always had friends but I remember when I was a child and everyone had 'boyfriends and girlfriends' the concept didn't seem right to me. Anyway, fast forward to high school and I had crushes on one of two of the girls in my class but they were quite masculine tom-boyish girls (in hindsight hah!). It was when puberty hit that things were different, the sense that I was different but could never figure out why began to make sense. I had the feeling I was gay, but I remember googling if it was phase because I just had crushes on other lads and I REALLY didn't want to be gay. The early 2000's were not socially like it is now, although no doubt much better than previous decades, I still just wanted to be 'normal'. A few years later and nothing changed but I never really 'liked' anyone. Anyway in the final year of high school I developed a huge crush on someone and I actually wanted to be with them. It was totally one sided and something I hugely cringe about now, but because I developed such strong feelings I began to accept that I was gay and the fact that I had lost all interest in women (even though to say I had any in the first place would be an extrapolation) was a pretty strong indication. It was still another 2 years before I would verbally admit it to anyone though haha!
TLDR;
So I 'came out' when I was 17, but in reality I knew I was gay when I was 12/13 - but I knew I ticked differently when I was a child.