A home type test is an immunoassay drug test (it works with antigens and antibodies and is in many ways analogous to home pregnancy tests) and for drug screening has a considerable amount of error. But quest diagnostics uses GC-MS drug tests (gas chromatography/mass spectrometry) is very accurate, is not able to be tricked with flushing, or aspirin, bleach, draino, vinegar... nothing. And yes, you're probably freaking out for no reason, it sounds like you don't smoke too often.