I Am 35 Weeks Pregnant Today, My Last Appointment Was

I am 35 weeks pregnant today, my last appointment was on January 19th they did a drug for THC and it came back positive, I took literally one puff on January 15th. The doctor said that it's in my file and CPS will be notified when I have my baby, I took one puff because my back was hurting, I was feeling nauseous, and I couldn't sleep nor keep anything down. I'm worried that CPS is going to take my baby if I don't pee clean when my next appointment on February 6th. Is there anyway I clean my system while I'm pregnant? I currently live in Michigan