Would my Doctor-Patient confidentiality be broken if?!

HIGHLY UNLIKELY! Most doctors are well educated and don't even believe Marijuana should be legalized. They will speak to you about it.

I have known one doctor to mention a minor drug offense to a police officer. The minor didn't even get his last name looked at and the doctor lost his license.

Remember when you tell him/her:
Your doctor won't care. No doctor still sane would. In fact, your doctor is probably holding far more secrets that are far more illegal. A minor drug offense will make the conversation interesting for a few minutes, but nothing else.

Brother's a doctor, has been for 9 years. He says that doctors are supposed to keep all secrets as long as they aren't life-threatening.

If you were dealing cocaine to children and then shooting puppies, that would be one thing.
But since you're a minor who just did a minor offense, the doctor is hardly even likely to remember a day after you told him.

if you HAVE then no, but if you ARE then most likely, just be careful about how you choose your words

i'm a doctor for 5 years soon 6 yay!