You have several options.

Make your own appointment to see your family doctor and they can start the referral process. You are old enough to do this yourself and that such visit be entirely confidential. Your family has no say in the matter.

Talk to your school guidance counsellor. They can point you to some resources including a school board psychologist. Either of them can act as an advocate on your behalf with your family. Again, your parents cannot deny you help.

Your community may have a centralised intake for adolescent psychologists.

Contact your local chapter of whatever your mental health association is and they can provide you with a list of resources including psychologists.

Check out support groups. My support group is open to students. If a family member wishes to attend the group may welcome this. I know my own group encourages this.

As a dependent you are entitled to those resources available on a parent's EAP (Employee Assistance Plan). Don't confuse this with the benefits plan. This is a resource of numerous modes of assistance - including finding a psychologist)

You are not alone.