I think many of us with social anxiety are very intuitive and are deep thinkers. Thinking about your thinking is called metacognition, and I think many of us do this more than the general public. Social anxiety is in our mind and we have a hard time getting "out" of our head. We create irrational beliefs in our head and struggle to let them go and think rationally (perception vs. reality). Please know you are not alone in your struggles. Many of us here feel the same as you.
From my experience, the more I think about my anxiety, worry about it and rehash past experiences, the worse it gets. I am working to distract myself when I begin to think about it. It is difficult to do because it is so ingrained in my head, but it is something that needs to be done. As Dr. Richard's therapy reminds us: The definition of insanity is doing the same thing over and over again and expecting a different result. If what you are currently doing is not working, try something else. Thinking about our anxiety and fighting to change it just strengthens those groves in our brain, while ignoring it will fill in the grooves until one day they will be gone.
When I was your age my social anxiety centered around talking. I worried that I would mess up talking to someone (slur, stutter, etc.). I thought about it and worried so much it made me avoid talking to people and I actually would make mistakes because I was worrying so much. Later in life I became a teacher and landed a great job where I felt very confident and was very busy. The combination of the two made me gradually forget about the talking issue. As my brain's neurons stopped firing with talking = anxiety, it gradually went away. I no longer have this issue at all.
I highly recommend purchasing Dr. Richards workbook and, if possible, his audio series. I wish I would have had this information when I was your age. I saw several therapists who had no idea what was going on and were of no help. Dr. Richards truly understands how we are feeling and the steps we need to take to reclaim our lives. Right now I am thinking of a few of his strategies you could apply to your healing process: Catch, label, and tell your brain the truth, and The "Look Around Technique". I have no gain in recommending this series. I just truly want to help anyone who is going through this nightmare.
The teenage years are difficult for a lot of people; everyone is carrying a heavy burden. Even people who seem to be happy are probably worrying about not fitting in. Seeming to not fit in in high school can be very difficult. People respond well to others who are kind. My suggestion would be to be nice and try to smile, look into Dr. Richards therapy (book: Overcoming Social Anxiety Step by Step and the audio series too, if possible), find an activity you enjoy doing and if you are good at it, even better! Try to exercise, listen to music that makes you feel good, eat healthy, get adequate sleep, relaxation breathing/muscle relaxation/mindfulness, and be kind to yourself.
The fact that you have located this site and have reached out shows you want to overcome your social anxiety and are making an effort to do so. I also recommend staying active on this site. It has helped me to read and talk to others who are dealing with similar issues. This community is here for you and cares about your journey towards overcoming social anxiety. Take care