All of the home tests I have reviewed are 50ng. Labs also offer a 50 and 20 screen and then the confirmation (such as you ordered) is at 15ng but is detecting only the metabolite (THCCOOH). For the purpose of standard tests you are below the cutoff level for the screen which means it would not go to confirmation. But that is a dangerous level (right around cutoff) which could result in a positive screen due to the allowable variance of +/- 20% for even the lab instrumental assays.

You should be completely clear very soon as the levels continue to decline. Already over 70 days....that's a long clearance time.