I have the same problem. Still waiting for my thread to be approved, but I'm confused by the fact that mental health quizzes have indicated that I'm schizoid, when I do in fact crave connections with people.
But what you describe here is exactly how it is for me, when I was a kid I had a few close friends and never wanted more than that. Ever since becoming an adult, I've felt like it's impossible to have that kind of friendship again. I don't know how to start being friends with someone, because in grade school it just kind of happened. You start playing with someone, you do it again the next day, next thing you know, you're best friends. It just doesn't work that way when you're an adult, it seems. I've had "friends" at work, but very rarely make the effort to see them outside of work.
One of the problems is that everyone else seems to already have their group of friends, and I feel like they don't need another one, or I'd be intruding or taking time away from their other friends if we tried to be friends outside of work.