I definitely agree about the school counselor. They would be the best starting point to getting help. Also, are you seeing a doctor or counselor to help with your schizophrenia and symptoms? They may be able to help or be able to refer you to programs that can.
If not, I would also suggest google searching for mental health programs in your area that help adolescents. It depends on where you live but they do exist and may be able to help with some strategies for managing school.
Also, if you haven't already you might want to look at our
Schizophrenia forum to see if others have some tips that have helped them.