You can buy home test kits at Walmart,Walgreens, and CVS. They are very accurate. But will cost you $15.00 for each test. Read the dilution method thread and use this the morning of your test. Many people have passed using this dilution method. I am about your same size. It took me 35 days to test clean on the home kits but I was a daily smoker for 15+ years 2-5 times daily. I also had 49 days clean before my ua. I did pass however. 3 weeks might me close based on your metabolism. Good luck.