How can I get help for depression and anxiety when there are no adults I can talk to?

I've been feeling like this for 3 years now and I can't bring myself to tell my parents because im terrified of what they will think, I can't go to the doctors without telling my parents and I've been offered help by a teacher but I just lied and told him I was fine. I know it's my own fault but I really really don't know how to get help, and I know I need help because it just keeps getting worse.