It is clear from your writing that you are not happy and that you need to find a way to feel better. What isn’t clear from your email is if you are seeing a therapist for talk therapy. If you were, then I would encourage you to talk to that person about the need for medicine. Sometime the conditions of a depression need to shift with a combination of talk therapy and medical intervention. An evaluation for an antidepressant may be important for you to have.
If you are not seeing a therapist then I would encourage you to go to your school guidance counselor and speak with him or her about the need to talk to someone and get a medical evaluation. By the way, that might actually get your parents’ attention — to let them know you want to get a physical to see exactly what the concern might be. Many other medical concerns can cause a depression, and once you are in front of a physician you can let him or her know.
You need to honor yourself by finding a way to get your needs met. I hope these suggestions help.