Urine or blood test
for presence of marijuana is not routinely done unless indicated and it does not show up in tests done for other things. So most probably your doctor will not come to know about it. Even if it is found out, you have the right to confidentiality and can refuse permission for disclosure to your family. Many states including California have statutes to protect teen confidentiality for specific services— particularly reproductive and sexual health, mental health, and drug and alcohol treatment. So you need not worry. But I would like you to know that marijuana is not harmless. It is especially harmful in your age as it hampers the brain development and predisposes you to schizophrenia
. So it will be better for you to stay away from it.
Hope you find this helpful. Best wishes.