I totally feel you on the part about your face turning red at the smallest things, story of my life! But, it's gotten better bit by bit as time goes on.
I would definitely recommend practicing breathing and relaxation techniques. The book "The Stress Answer" by Dr. Frank Lawlis is very insightful, among other things, and may be a good read for you. He goes into detail about high tech therapies and brain scans, but gives techniques for us regular folk that can help achieve similar results! I would also highly recommend meditation. I got started with a book that my mom would read to me when I was younger (I was diagnosed with generalized anxiety disorder at eight) that had guided visualizations. Now I use a bunch of great free podcasts on iTunes such as Meditation Getaways, Meditation Station, and Relaxation from Inner Health Studios.
None of this is a quick fix, but in my experience, there really is no quick fix for anxiety, depression, mood disorders, etc. Although it will take time and perseverance, it will pay off! I have made remarkable progress in the last year. Last quick suggestion is to find a therapist/counselor that you trust and can talk to if you don't already have one. It can be talk therapy, CBT, or any other kind of therapy that you feel is beneficial in one way or another. Although I don't practice a significant amount of CBT with my therapist, it is really a big help just to have someone that I can unload my worries onto that can really get me thinking about things in an objective manner.
As far as high school goes, I know it is pretty much hell on Earth, but stick it out! I just graduated this spring, and it was such a relief to have it done and over with. Just think, you're 75% done already! I had such a nervous breakdown my junior year, that if my parents had let me, I would have dropped out and gotten my GED. Although it was a bad year, and it was really hard to go back, I'm so glad I did it and I would really regret it if I didn't finish. Despite all of these setbacks, I graduated in the top 10% of my class and have received $55,650 total in scholarships! Whether you plan to go to Harvard, community college, join the military, or go out into the work force, I promise you that you will not regret getting your diploma.
While I'm finishing up giving you my two cents, the most important piece of advice I can give you is to recognize your accomplishments. Don't compare yourself to everyone else, just you. Whether it's making an important phone call, going to school and doing your best to handle your anxiety, or anything else, recognize that you have accomplished something. Even if it's something that would be no big deal to someone else, recognize your success. And even when something goes really wrong, try to find something positive about the situation. Well, I hope some of that sacred wisdom helps haha:-) I wish you the best of luck, and feel free to message me if you ever need someone to talk to!