You do need to mourn for the things that you would have liked to do and didn't get to do. Those are legitimate losses, and they do affect you.

On the other hand, why keep accepting that you can't start on the things you wanted to do now? You don't have to accept those limits. If it means enough to you, you can find a way.

I always wanted to be a psychologist, and I gave up on that career goal when I was 18 because a professor said in a lecture that they didn't want people like me. I wasted a lot of years thinking that I couldn't do it, and I told a lot of people that college was just a waste of time and money that never got me anywhere because my degree meant nothing to anybody. It hurts that I wasted all that time being depressed and thinking that I couldn't do it. I don't know if I'll ever get a phd, but I am going to be a counselor, so at least that is something.

I had all the thoughts like you, that I could have been someone by now, etc. That stinks to feel like you aren't someone. You are someone. But if you're not the someone that you want to be, make up your mind to become the someone you want to be, and not to be limited anymore. It's scary, but isn't it scarier not to?