You can talk to your parents, a teacher, your doctor, an adult friend, anyone. What is important is that you seek help.

You doc is always your best ally when it comes to any aspect of your health, beit mental or physical. You doctor is legally obliged to get you help, to get you a therapist, give you some medication, ect...

You need to tell your parents what you are feeling and what you need. Tell them that you need help, that you have thoughts of hurting yourself. I am sure your parents will help you to get help.

When in doubt, an emergency room is always a good place to get some help. If you present yourself to the emergency room and say, "I have thoughts of hurting myself, I feel overwhelmed, I need help" I guarantee they will get you help. Every emergency department as a psychiatrist on call who can talk to you, and help you to get more permanent help.

I always say this, and it bares repeating every single time:

If you find yourself in need of immediate help call the police (or an ambulance if you have hurt yourself), a suicide hotline in your area, or present yourself the emergency room.

There is lots of help out there for you my dear. You just need to ask for it. Talk to your parents and your doc.

Good luck