Since behavior, thinking, and chemistry all influence each other in complicated ways it's always a good idea to tackle your difficulties from different angles. You stated that feelings of inadequacy have been a longstanding problem for you. Chances are they preceded or even provoked the onset of depression. Depression and loneliness are extremely common. You say that you have nothing whatsoever to say or contribute when you are with others.
Workshops are often available at school for free and self-help books are plentiful.
Ask your counselor to recommend some good ones. And don't forget to consider the basics. Maybe a yoga class can help. You mentioned that you break out when you are anxious. Again, you can approach this problem in several different ways.