You're good. Blood tests don't last as long as urine tests. There's been some debate about this, but in my experience this is the case. THC lasts in the blood for a few hours, up to a few days. If you have been smoking on a daily basis for a while, blood tests have been known to read up to a month after quitting. You're good though. Doctor's usually don't test for THC unless they have reason, like you got caught, and if you're 15 or older, in most states in the US it doesn't matter because you have confidentiality with your doctor. You're good, don't worry so much.