Please do not worry. Based on what you have said, you are unlikely to have a testing problem. I would, however, recommend that you drink lots and lots of water the night before and the morning of the test. The lighter your urine the less detectable toxins of any sort are. Having had my share to piss tests and close calls, I'd say your worries are a bit much -- understandable because you don't want any trouble, but a bit much nevertheless. If March 2 was the last time you toked up, you should be just fine.