I get that when you went anxious you feel sick. I just got off a plane that endured turbulence and felt so sick and had a panic attack. Years ago I started to feel nauseous from anxiety and was prescribed stemetil for it and it worked maybe mention that to your doctor, it might help.
I stayed indoors for 5 years and I regret it so much. Saying get out there and live your life is easy to say and much harder to do but try and push yourself a little further each day.
Have you sought any professional help or advice? Counselling might be a good idea as you need to get to the root cause of this. I'm sorry to hear that the people in your school aren't very friendly, that is not nice but something you must deal with in what way you can cos you cannot change them only yourself.
I really feel for you and know a lot of what you're going through. Keep me updated please,you can chat with me anytime.