A lot of people figure themselves out later in life, so I don't think you can apply the "late-bloomer" label to something like gender identity. Some folks don't figure it out until they are in their fifties, and I swear it seems like they have more fun than some younger folks.
But, I guess I didn't know for sure until I was about 17. Well, rather, I just didn't know there was a word for it when I was kid, and couple that with the fact that I like guys, I really just figured I had to be a straight girl. But when I look back at certain events in my life and certain memories, everything seems to make more sense to me. The important thing to remember is that identity is a very personal thing, and it's okay to take the time to figure it out for yourself. My other bit of advice is not to get too worried with fitting into a label perfectly. Plenty of transguys, like me, adore girly things or wear women's shoes or whatever.
On the topic of body dysphoria: you don't have to use that as an indicator. Some transfolks have extreme dysphoria about their bodies, some only have it in regards to certain parts of their bodies. I hate my chest, my hourglass figure, and my voice but I feel relatively comfortable with my narrow shoulders. I don't like anything below the belt, but I also don't hate it either. I am sure that there are lots of non-op folks out there who choose to live in their natural bodies because they are comfortable with it.
So, take some time to look around, get advice from others, and don't get so caught up with worrying about if you are really something.
Take this time to take a deep breathe and take it at your own pace.
