Cystic fibrosis so worried?

I'm going for a sweat test for cystic fibrosis next week cause i asked for one from my doctor but my mom told me later i had one when i was 4 that came back negative im 19 now and for 3 years have been dealing with cough or a grunt that brings up mucus in my throat and a stuffy nose when i get upset it gets way worse like the mucus starts comeing out crazy do you think my test will be negative ive heard in cystic fibrosis you always have mucus in lungs but doctors never hear anything and a ct scan showed no fluids but i do get sinus infections offten but only get bronchitis once a year i accutally started all this after a bad bronchitis