Allyda, your post was very touching. =)
I think, however, that we shouldn't think about things that "we could have done earlier". It usually leads to nothing more than frustration... I'm sure it's tough to swallow having spent many years wanting to do something you never did, specially something like a transition, but I think that every person, cis or otherwise, at one point or another regrets not having done something earlier. Whether it's a sport you love that you think you would be better at if you had been interested in it earlier, an instrument that you were fascinated about and now see children playing it better than you do and you realise you won't be a rockstar, there are so many things that every single person regrets "not doing earlier" in their lives... I understand it is frustrating, but wishing to live your life again and do some things different is something that every human wonders about, not just transgender people. I see that frustration in these forums of course, but also on my parents, on friends who're my age and even on myself. Sometimes it feels like even I only decide to pursue things when it's already "too late".
My point is, even if you had transitioned earlier, today there would still be things that you'd wish you had done different. I think it's part of the process of growing up.
Even if you had transitioned at an earlier age, today would still be today. The years you fantasize about would still be "lost" because they'd just be memories. I think what matters is the now and what you're doing for your future, not what you could've done before. Transitioning at a late age, you're going to experience new things, you'll feel novelty, you'll feel joy that I think most people your age with more "conventional" lives don't get to feel all that much anymore. Even if you had been cisgender, you'd have regrets of some kind about your past, you would still think of your "good years" as being gone and feel grief/regret, it's just human nature. In fact, you would probably think your true happiness is in the past, rather than the future... but since you are transitioning now, surely your perspective is different and you think that your happiness is in the now and the future. I think that's the way of balancing things out for people like us? We're full of hopes and dreams, regardless of what age we transition at, therefore capable of being born again at any point in our lives.
I hope this post made any sense. Age is just a number, how you choose to act and present yourself carries far more weight in others' perception of you than your age does, so there is nothing that you could've experienced before that you cannot experience today or tomorrow. I don't mean to trivialize or seem insensitive towards the frustration that comes with waiting so long to do what you always wanted to do, I know it's painful because I feel it too, but if you analyze things with the future also in the picture, you realise that it's not impossible to be happy. =)