Hi there - yes, that'd be me Jamie is referring to, and my story is pretty similar to yours. I first let myself know I wanted to transition back when I was in my 20's, but shoved it away, and spent 25 years trying to "pass" as (among other things) a gay man, until one day I woke up and smelled the oestrogen.
I'm now 2 years into transitioning (in the UK), and have my pre-op consultation due next month (since I want gender affirmation surgery, which not everybody wants). I think you could just really let yourself be yourself, and find out who that is now. As has already been said, many people don't transition until they're older, out of fear or uncertainty, or simply because it was that much harder when we were young. In my case it took me longer because (a) I had some abuse issues to sort out first, and (b) it then took a while to realise I was a "real" trans woman, because the woman I am is pretty much a dyke, and not feminine, and most of what you get to hear about trans women (until you dig a bit deeper) is just stories of the ones who "knew since back when I was being potty trained" and who wanted to be princesses and do the dresses and dolls thing as a kid (all my heroines were Trouser-Clad Adventuresses like Amelia Earhart). There are billions of different kinds of woman - and they're all real, all valid. (Come to that, there are billions of different permutations on gender identity, so it's fine if the label "woman" doesn't tell the whole story on its own - there are plenty of people for whom that's the case.)
It's not too late to discover yourself fully - though you may have to go through some grief for not being able to do it sooner, alongside the joy and relief of being yourself. Have fun exploring! I would recommend finding a good gender therapist and a support group to help you do this, and steer clear of anyone who seems to be more certain than you about who they think you are

. And be patient with the people close to you who will need time to catch up with you. And be patient with yourself too, don't try to rush a new identity - transitioning is pretty much a fresh adolescence, and you know what *that's* like...