My life has been very much larger and more complicated than simply undiagnosed, untreated GID, and I honestly don't feel I would have been ABLE to deal with it sooner than I have. For me it's more like okay, now it's time to deal with this, and it's a huge and important piece of who I am, but I don't feel my life up until now has been wasted. It has been hugely difficult and painful in some ways, but it has been very rich and interesting in many ways, too.
I find that for myself regrets are mostly fueled by hindsight, illuminated by knowledge and resources that I have now that simply did not exist or were unknown to me then.
I grew up in a deeply fundamentalist repressive and suppressive Christian family, and although my family has always laughingly told stories of how when I was a toddler I wanted to be a boy, if I had persisted in that beyond an age when they could find it "cute" they would have put me in a mental institution, or worse. Seriously. I'm sure many people here can tell similar stories. I grew up simply making the hard shell around myself thicker and thicker, so it's taken me years longer than some people to dismantle it and break myself free.
This is my life, and this is where I am in it, at 51, and I'm okay with that. And I've been through enough major stuff to know that nothing is a magic bullet that's going to fix everything. I will always have the same genetic tendency to depression, and I'll still have whatever relationship issues I've always had, and so I'll keep working on those things and learning how to manage them, and some of them will get better, and some of them I'm sure I will struggle with in various ways for the rest of my life on earth.
I'll still be me after my better-late-than-never transition, I'll just be wearing, as Ram Das puts it, a different and more comfortable "spacesuit."