surprise drug test

i am 19 and i have been smoking everyday, a couple of times a day for about a year now. when i found out that i was going to be hired on full time at my job, i knew that i had to pass a drug test. My boss told me 2 weeks ago that i had 30 days to clean up. well i still smoked for another week and then i stopped. i have been drinking water like crazy since then and i sweat all the time. i fell at work and my boss made me go take a lab urine test. i freaked out and told him that i knew i couldnt pass it. i went anyway, then i went to the temp service and took a cheap test, it came back positve. the next day i found out that the lab test came back negative, they had me take another one, and it also came back negative. So you would think that i still had my job, but the company is slow right now and are letting go of people and they are saying since i am already gone they should let me go too. i think that its not right, i proved that i could overcome what everyone thought i couldnt do.