First Of All, I Use Meth And Marijuana Daily. I

First of all, I use meth and marijuana daily. I used a catheter and completely irrigated my bladder by using water and a big syringe to extract the water. I did this 2 times then filled my bladder with clean water. Then I urinated and tested it, and it was positive for methamphetamine, but not marijuana. How can that be? Also there was visible mucus in the testing sample. Could that contain the meth?