newborn screening

we received a call today that our sons newborn screening flagged for cystic fibrosis. i completed genetic testing with myriad and was found to not have genes related to CF. my husband had not been tested so i understand he could be a carrier. i also understand i could be a carrier for a mutation that wasn’t tested by Myriad. we have a sweat test scheduled for next week but im in crisis mode. i’m wondering if anyone has any experience specially with myriads testing and how likely this is to be a false positive based on my testing negative? or really just any comforting words. the newborn phase has been so rough already and now i’m spiraling regarding giving my son a life set up with health issues.