How do you measure the levels of THC in your body? like with weigh, height, etc.?

Soo.. Im embarred to ask this, but uhmm.. So I had a urine test for a pre employment job and I took the home test before I went and ped it!.... but does that mean I ped the real thing?? The lady is supposed to call me today and tell me.. Its been 3 days since I last smoked and 1 month prior to that.. I weigh 115 and im around 5 6 in pretty good shape.. Its really had me worried.. I mean I did all that crap like detox, craneberry juice, h20, exercised a bit.. But I still have my doubts.. Anyone??