Wow. This was both sobering, and yet somewhat uplifting. I can see how one could get hung up on all the notions of "what could have been", but consider everything that had to occur for you to do what you've done. It's so easy to say "life would be better if I had just <x>", but we can't be certain of that fact.
If anything, I take solace in knowing that my path through life has been primarily decided on my own. The establishing conditions and circumstances weren't, but upon adulthood, I was effectively forced into freedom. At first it was disorienting, overwhelming - growing up in the suburbs and attending a private high school were everyone was of homogeneous race, gender, and creed really left me sheltered, and to be suddenly thrust into living conditions with people of all walks of life was exhilarating. This was freshman year of college, and my first exposure to actively making my own decisions in all aspects of my life.
It's been a while since then, but everything I've done, all I've accomplished and studied and earned, everywhere I've traveled and everyone I've met - it's all been of my own volition and drive. We may not experience the world in its entirety, but the path we carve is unique. We are not defined by the doors we close or the endless "what if?". We are not insignificant, we are not lost. We should not despair over alternate histories and theoretical outcomes.
We are our choices, for better or worse. And we can always choose to change.