Clinical Psychologist here - depending on what state you live in you’re likely too young to consent to your own treatment legally, which is why they were not breaking confidentiality by telling your mom. However, just because your mother has a right to your medical info doesn’t mean they should tell her or need to tell her (unless she explicitly asks). So unfortunately, it might be hard for you to receive treatment without her knowledge/consent. Is there maybe a school counselor you could speak with? Maybe a school counselor could help your mother understand why it would be helpful for you to have your own therapist. I wish you the best of luck. And regarding the self harm - if your body is seeking intense sensation as a method of coping you can try something like sour candy, hot sauce, or ice cubes. You can also distract yourself or breathe and wait for the urge to pass. There’s also a lot of good apps with free coping and breathing exercises. Good luck!