How long does it take for THC to get out of your system?

I am 5'8 and weigh between 135 and 140. I use to smoke a lot, but I stopped smoking in the middle towards the end of April. I don't exactly know the date. I probably will have a drug test coming up either within the next 2 weeks or early July. I'm not sure if the THC is completely out of my system. I know that take home drug tests only test for a cut off level of 50 ng ml, but lab tests do a 15 ng ml cut off level. Does anyone know if they think I would pass a 15 ng ml level cut off? Or if they know of any THC 15 ng ml level cut off take home drug test kits?