CPS WILL bust you if you pop dirty and they do drug test moms, some places test every mom (I was). They also drug test babys poop, usually only when mom tests positive, because meconium holds drug residue for many, many, months (3-6). Please do not think CPS has bigger things to do, because it just doesn't work that way. They take drugs seriously, often even more than actual abuse. (awful but true!)
My friend (when I was in TX) got caught this way and had a year long PITA with CPS. She had to take classes, get drug tested, and any mess up meant loss of kids, even temporarily. She was lucky that she got a reasonable case worker! This was in the liberal city of Austin. It was a huge mess, and will always be out there even years later- not good if you don't want CPS issues.
So, the best thing is to quit now so that you are clean when you give birth. Don't wait, you never know if you will have a preemie and thus still test positive. If you still have nausea, try the Zofran. It works fantastic and I have never know anyone to have issues from it. It's highly effective, legal, and safe (years of use and study back it up).