How do i escape this "loop" of anxiety

Hello everyone, i'm just a regular 17 year old guy with a few problems. I saw that you guys have helped a lot of people here so i decided to ask you to help me.

The problem i have is rather complicated. The thing is i might have a form of social anxiety. Let me explain. I am not the type of person that sits in his room all day in front of the computer doing nothing. I love science, i read books all the time and i also love programming. I am able to manage my time so i can study, read books, watch movies, practice programming and socialize.
I usually enjoy being alone and reading books but i know that is not healthy and it will make me feel lonely if i do it for a long time. That is why i go out every day to meet and talk to people.

What i mean to say by that is that i am not completely anti-social. I have no trouble meeting people or talking to people. I don't feel anxious when talking in front of 300 people. However i cannot understand how social relationships work. Even though i am able to meet people it is extremely hard for me to understand our relationship. I do not know if someone likes or dislikes me. Should i talk to that person or will i be annoying? If i don't talk to them they will think i don't like them or they will forget about me. Do they want to see me? Does that cute girl like me or is she just being extremely friendly? Why does that person doesn't talk to me even though yesterday we were hanging out? Did they do that "thing" because they doesn't want me here?

If someone does something that might feel like they got "less friendly" towards me i get super anxious and i fall in depression thinking i did something wrong. That person may be not truly be "less friendly". It might just look like that in my eyes and even if i know that, i am still anxious. Those are thoughts everyone has at some degree. But i become so anxious that i might stop going out for weeks. I have been trying to fight that anxiety, telling myself that i am just being stupid but i now gave up.

Let me give you an example. This summer i decided i would put myself into a test. I took part in an event that had to do with computer science. In that event 300 strangers from all around the country would stay in the same hotel for a few weeks and work together in a project. Everyone also had a roommate that they met for the first time. As you can imagine i would live for a few weeks with random people and would be forced to get to know them and work with them. Now this indeed helped me understand things a little bit better and become better at social interactions. When the event was over everyone was really sad. Most people were crying because they probably wouldn't see each other ever again. We made a group in messenger and said we would keep in contact. In the first few days everyone was talking to each other and they were saying how much they miss them. Now its been only a month and no one speaks. That troubled me, because i thought i understood how much they liked each other and now i see i was wrong. And i have fallen into depression again. I don't know what to do... There are other things that trouble me but i think you got an idea. I also want to say that those feelings do not occur when it comes to really close friends, unless if i don't talk to them for months.

Sorry for my english