In My System 50 Days?

Hey all, I'm pretty new here and mostly interested in the cooking section, but I just ran into bit of trouble and I'm curious what you think.

I knew I was job hunting so I stopped enjoying my greenery roughly 50 days before I ended up having to take a drug test, and I lost some weight, drank a ton of water, etc. Well I got a call today saying I failed my test! I was shocked, to say the least. I figured I'd be totally fine any time after the 3 week mark, apparently not.

Relevant info: I'm not into smoking much but I go through about an oz a month in edible form (or did, for a few years, before I stopped this summer for job stuff). Would that make a difference? I didn't think I'd have a problem.

Any thoughts about how long it'll take to be fully clean? And/or why it stuck around this long?

Preemptive thanks for your help everyone!

Thats exceedingly strange, with enough water and excessive i can be clean in 3 weeks and i smoke more than you eat a month.
That being said, its all about your metabolism since THC is fat soluble. So i guess its not unprecedented... Just odd.