I just posted on your post in the introduction section. If there is a counselor in the school you go to, please reach out to him or her. Or a guidance counselor. As I mentioned in my other post, my daughter, who is now 18, struggled for many years with some similar issues as you are describing. Concentration, failing classes that she'd normally have no problems with, social anxiety. Please reach out to either a school psychologist or social worker in your school, or if you don't feel you can do that, maybe you can discuss with a school nurse or even your family doctor. They may be able to convince your parents to consider getting you a therapist.