toomuch- First of all, congrats on the therapy, it’s a big, hard step to take. About your Shabbaton, I would tell you to not overthink it. Stick with your friends and just relax. It might feel like everyone stares at what you are wearing or doing, but no one really cares. If they do, they’re not worth impressing. Just be yourself, stick with your friends and try to forget about the other over-confident people.
I was also depressed in high school but I didn’t have the courage to tell anyone, let alone go to therapy. I finally told one friend and it seriously changed my life. Definitely tell your friend(s). You need a support system in high school. You’re lucky you have friends, tell them.
Let us know how it went.