I'm under my moms insurance. I'm 19 & have a pap smir in a week. I want everything confidential & I don't want em tellin her that I want it conf. If my mom asks anything about me, will the doc say im fine or that I requested it to be conf.?

Adult. You're an adult, age >18. The doctor cannot tell anyone, including your family, anything about your medical history, diagnosis, or care without your permission. The only exception is if you're incapacitated or if ordered by the government/court. The doctor can't lie though - if you don't want him to say anything, he'll just say to your mom that he can't discuss it - legally.
Confidential ;but... The doc is obligated to follow your wishes but the story does not end there.Since you remain under your mothers policy,she will likely get an EOB,explanation of benefits, from the insurer that lists what they paid for.This is often listed as an office visit and could list testing.