Anxiety Support Group
Anxiety is a physical condition marked by intense and persistent feelings of distress, fear, angst or dread. General anxiety caused by routine day-to-day stresses usually passes quickly and is experienced by almost everyone at one time or another. However, such feelings that linger over time and are very difficult to cope with, and which lack a clear cause, may indicate...

Get her a book on Social Anxiety written for teens if she won't go
to therapy.
I believe my most useful tool in helping children/adolescents conquer their fears and anxieties is a mantra I never speak aloud. "Ears open. Mouth shut." I speak just often enough to let them know I am listening and restrain my commentary to reinforcing their self-confidence.
E.G.
*Good idea."
"Solid observation."
"You most certainly could do that."
"There's an option worth developing."
The goal is to help them sort and believe in what they already know and leave the experting to the experts. I'm just a sounding board who cares enough to share a bowl of ice cream while they sort their own strictly personals. Well. . . It isn't pure coincidence that I always happen have their favorite munchies in the kitchen. There is nothing like a tasty treat to get the mouth in motion.
But that is me. . .
Gentle support while you find what works for you. Listening. . .
If you think your daughter needs professional help, try to encourage her to consult with a doctor. Therapy and medication would be helpful. I pray that she will overcome this fear of dealing with people. Please keep us posted. God bless.
You've taken the important first step in writing it out.
This is a hard one to do. You will have to remember that this is not your problem. You are responsible for what you say, do, react, and how you respond. You are NOT responsible for what others say, do, react, and respond.
Suggestions above are all excellent. In order for her to find her better balance, she has to reach out for it.
You're doing a wonderful job in showing her support, encouragement, and understanding by sharing it here.
Best wishes as both of you find better balance.