I agree completely. My twenties were the most frustrating, lonely, self-defeating time of my life. My ideas about how the real world worked were so totally wrong, and it took me a long time and much pain to figure that out.
I think your timeline is pretty accurate, although now I'm reduced to hoping that things start "rocking" for me in my '60s!
Bleak and hollow... I know all about that, believe me.
I once read an article about people who commit suicide by jumping off the Golden Gate Bridge. They interviewed one of the rare survivors, who said that he jumped because it seemed to him that he was facing so many problems, all hitting at the same time, that he could never solve them all, and that ending it was the only solution.
He said that the instant he cleared the railing and the edge of the roadway, he realized that every single problem he had could be solved, except the problem he had just caused himself.
I’ve found Stoic philosophy—in particular the writings of Epictetus (Enchiridion and Discourses)—to be very useful, as well as very easy to read.