Isn't there anyone you could talk to: a counsellor or psychologist as it seems the turning point of your life was triggered by your grandfather passing away.

You should not rely solely on quizzes to determine whether you are (clinically) depressed or not. It might not be easy from what you said, but it is best to talk to your parents. Put your cards on the table and tell them how you feel, what is happening in your life and how unhappy you are. In all likelihood, they are aware that there is a problem (your behaviour, how it is affecting your work) and would most likely be eager to get it resolved.

*If* they do not respond, which i think is unlikely, a doctor/psychologist might be the next step to evaluate your needs and advise you best as to how to proceed. But do try to talk to your parents as your first port of call...