you should at least save some of ur own clean pee and freeze it for further use.

And with regards to the faint line, it is either a pass or no pass test with those and the color strength of the line is usually not an indication of how close to the cutoff one is. When i took an at home test, it was very faint and i was/am clean, but took a couple bowls one night. I had time though to send it off to the kit's lab and they confirmed it negative.