Dunno man, I don't want to be contrariant, but it just sounds like you were privileged enough to think that way now.

I was poor, I didn't really get to go clubs or extra activities besides classes, neither did I made any lasting friendships.

Now I'm in my 30s and I'm living my best life. I have a job I can enjoy, enough money and a loving partner. Never have I thought that it would be nice to go back to school. Hell, I haven't had contact with anyone from school since it ended.
I do have some fond and grateful memories of some teachers. I think about them from time to time, but I don't really miss any of it.
Also, I'm from a country that has decent enough public school system.