how much weed do you have to smoke to show up in UA drug test

hi all,

i started smoking maybe 2 years ago, but it was only very randomly in social settings. recently i have been doing it more and more. if i have to give a good estimate, i would say i've been smoking about 1 bowl about 4-5 nights a week for the past month. (i'm a female, 27, 5'5" and about 150 lbs.. i don't exercise all that regularly but am pretty active at work and i don't drink as much water as i should, but i do seem to have a pretty good metabolism, for what it's worth.) i recently had a scare when people at work started getting random drug tests. the last time i smoked was this past thursday, and over the weekend i ordered i FDA approved UA kit for marijuana to test my levels. today (monday) it arrived, and i followed the steps exactly, and the test came back negative for any weed. the test said that negative results could indicate a level below what the test is testing for. i really don't think the 4 days (from thursday to today) made that big of a difference in getting anything out of my system so maybe i just don't smoke enough for it to show up?

i'm considering maybe cutting my smoking back, say 1-2x a week, and then continuing testing myself to see if i'm still undetectable. i'm just super paranoid about getting hit with a random drug test at work and losing my job. i know everyones body metabolizes things differently and it takes a different time for everyone time get things out of their system. however my question is, in general, how much weed does someone have to smoke for it to show up on a urinalysis? if i cut back to 1-2x a week do you think i would be still undetectable?