well, unless you're 4'11, you're probably relatively slim, so this is good.

lots of posts from young skinny folks cleaning up much faster than other older heavier smokers!

probation probably means observed, so not much chance of subbing

drinking water in the days before the test doesn't do anything. most people say niacin is a myth and won't help either.

Buying a THC hometest will give you an indication if you can pass or not.

You are possibly a candidate for dilution. Read the dilution sticky. Load up on creatine a day or two before the test and drink gatorade instead of water. This will put more creatinine and specific gravity into your highly diluted urine, so your test results (hopefully) won't indicate you have diluted. Take some B2 or BComplex to color your urine yellow. If they mention the vitamin yellow color, be cool and just say you always take a multivitamin every morning.

Best of luck!