Hi. I'm a mom of two teenagers and a person that gets anxious in social situations myself. I term it that way because getting nervous in social situations is a bit different than social anxiety. I am sorry this is all so tough on you. I know it feels bad. I was very anxious socially until my first job that had me talking a lot with the public. I had to. It was forced at first but I found the more I did it, the easier it was. I'm told by my kids now that I can and will talk to a wall and no person is ever a stranger. I can chat anyone up with ease.
I have a son with anxiety. He has a difficult time in situations that require him to interact and freezes up. Stays silent a lot. He's determined that this is okay until he is more comfortable. He also has a hard time raising his hand in class. Doesn't like everyone looking at him and it's an opportunity to feel embarrassed. He might say or do something wrong. But since it is often a part of the expectation of the class, he does it.
You are going through a very tough age. You think everyone is watching you when in reality they are worried about themselves. You over scrutinize yourself. Negatively talk to yourself rather than give self care. You're doing great! You try every day! And I will tell you that the more you are exposed to social things, they easier this becomes.
With that said, you do sound a little anxious and I encourage you to express this to your parents. A therapist can be of great help.
Some people prefer their own company most of the time and are fine. Some avoid others out of insecurity, which isn't fine. I don't know which one you were originally, but now it sounds like you're judging yourself pretty harshly over it and it's making you unhappy, so whatever it started out as, it has become a problem for you. On the other hand, you're 13, which means you could be someone else entirely when you're 14. Life is like that at your age, you change fast. What concerns me is you saying you are at least somewhat afraid of school starting again. When this kind of thing happens to someone as young as you were when this began, it's highly possible something happened to trigger it. A good therapist can help you figure that out. Your parents might be able to help you figure that out, depending on the nature of your parents. (Mom above is very engaged with her son. My parents were not all that engaged with their kids. Families are different, and the way people raise kids differs in different eras). You can also help yourself by trying to not avoid things that make you uncomfortable. As long as they are safe things to do, try and do them anyway. You probably find that with time you just settle in. As for the friends and boyfriends thing, you have 13 year old friends who have that kind of boyfriend? That's more advanced than I was. But that is a lifetime problem. When you get a romantic relationship it will happen with you as well. That's just the way things are. You have to learn to share your friends with romantic partners. That won't ever change. You'll get used to that. too. Your ability to be by y0urself will serve you well in life when this happens, so that part of this is a positive thing. But do work on the anxiety part. Peace.