help. drug test soon

hello, Ive been a pretty heavy smoker for the past few weeks (1-3 times a day) and i just got caught by the parents because of the stupidity of one of my friends. officially my parents have no proof that ive ever smoked but they are crazy and want me drug tested anyway. initially i had a test scheduled for october 23rd but im fairly sure its been moved back which would obviously give me more time. My parents threatened to take my car away for 6 months if i fail and they are crazy and probably would do it too.Im getting tested at the Doctors office and ill be 18 in a few days. baisically im asking what I should do. im guessing that i have a month and a half until the test. ill be 18 then, is there any way i can have my doctor lie to my parents? I know that he can't tell them the truth if I dont want him to but if he says nothing my parents will know I have something to hide anyway. helppppp

All I got to say is.....you make it to easy

Just tell your parents the truth and say its just pot. No hard shit.