How to deal with post college loneliness

Feeling so lonely after a year out of college

So I'm a 25 year old man, not from America. Recently (2 months ago) found a decent job and got an early promotion, people at work are also super lovely and we have a lot in common and laugh and joke around, but I just can't shake the feeling that it's a temporary work thing and doesn't go any deeper than that or last any longer after switching jobs.

I actually felt this way after going to college from highschool, since my highschool was so big and I had dozens of friends and like 5 or 6 different friend groups, but my college was so small and after a while I found myself disconnected from 99% of highschool friends while I only made like 1 or 2 friends in college who I talk to regularly. There are other people that I can reach out to once in a while, but they are more of acquaintances.

I just feel wo lonely at weekends, and even when I do go out with friends, it's just one on one and there's not really any freind group going on other than in the office.

I do not live in America, so I still live with my parents like everyone in my country, and I've never invited anyone over se it'd feel weird if I were to start now.

I also have to mention that I finished my classes last winter, and been working on my thesis and finding a job since then. Now that I've found a decent job, I just feel so damn lonely specially at weekends. Wanted to see if people wih similar experiences exist, and what worked for them to fix this. I just have this deep feeling that nothing as social as school or college will ever happen in my life again, and I've missed my only opportunities like an idiot because I was too lazy to go out with people.