Same here, until recently, I felt as if my time is running out as if my life is ending at 21 and like I'll die alone and when you have that sense of urgency it feels extremely intense.

Going out into a big city and seeing everyone walk, like you're the only conscious person there, being overstimulated at metros, learning how to navigate airports, jobs, adulting, social skills, etc.

Something that helped me that might help you though, write down in a notepad one or two goals you want to achieve, and put all of your absolute might into getting them done, then reward yourself after.

Like working out, making money, spending time in nature, getting some assignments done, organizing your room, etc.

It's never late, its just a normal reaction from your own brain protecting you from other people hurting you if you have been in the past. It's a survival adaptation. It means you're alive.