I think I've gone through what you're feeling right now countless times in my life so far. And it didn't matter how old I actually was or what I might have been missing out on in the past, I just always seemed hopelessly late in trying to catch up with the life I somehow seemed supposed to lead like all others.
What you need to do right now is to stop running after some standard like a Fata Morgana in the distance and stand still by yourself. You are you, exactly as you are. Comparing yourself with what you perceive as standard living and feeling you didn't have that in the past is going to cause you nothing but feeling ashamed of yourself, and feeling ashamed has never helped any living soul.
I believe we create standards and try to fit life into them to help us feel a bit safer in a world we perceive as chaotic. We box life experience up and label it. But that is not the reality of life experience, it's like standards are just mental safety margins for the human sheep in us, within them we are free to feel safe, out of bonds social conditioning has you feel all alone and lost at sea. The universe didn't hand you out with a manual tatooed on your back or a list of things-to-do-before-you-are-thirty, so I think it's perfectly safe to show yourself the same love, acceptance and respect and not limit yourself to some standard.
And I tell myself that if it was necessary to change the past to live a fulfilled life, creation would have provided the option. Since travelling back in time doesn't seem to be an option, I have to trust the Universe that I simply don't need it to make my soul's true desire come true.
Now apart from that, if you feel like what you need to do to get your life on track is almost impossible, first on whose tracks exactly are you trying to get your life on? Are those really yours? If after inspection they truly are, feeling ashamed for your past and beating yourself up over seemingly missed chances eats up an incredible amount of your energy, so you feel deadly exhausted and lack the energy necessary to bring about a positive change, and live your life more in tune with who you really feel you are.
Since you seem so low on energy right now, if you have some counselor whom you trust, do go and talk to him. Just telling another living being face to face exactly how you feel will help you to get it off your chest and be a relief to you. You need lots of support right now, all you can get really. Being depressed is like suffering from major blood loss to a point where you've exceeded your resources and your body has trouble going on, and you're just very tired and want to sleep. You're not dead in spirit, it just feels that way. And it really helped me to talk to someone whenever I felt I couldn't go on anymore. It's not the final solution but a reliable first aid.