What is your concern about telling your parents? How do you think they'll react? Are you worried about disappointing them? Have they been unsympathetic, uncaring or abusive?

I ask because if you're in high school and you live with your parents and you're dealing with a significant degree of depression, it is going to be very hard to go get the kind of help you need without their assistance, much less without their knowledge. Do you need to tell your parents before going to see your GP? If you absolutely don't want to, you can probably find clinics geared at adolescent health where you can go without your parents' insurance. Call around.

You can always ask before disclosing anything (to a counsellor or a doctor) what are the limits to confidentiality for that person. You can ask your counsellor something general like "what resources are available to help a student who is dealing with depression?" You don't have to tell them much unless and until you feel ready.

Good luck. I hope you find the support you need.