Help! CF testing!

My little girl is 3 months and is failure to thrive despite eating normally and eating the amounts she should be. She has always had a wheeze and some trouble breathing at times but when we asked at her 2 week appointment they said as long as she isn’t losing oxygen then not to worry. That was a different doctor.

So fast forward to today, weight isn’t good and because of her breathing she is getting sweat tested for cystic fibrosis next week. We did labs today, blood and urine, and those both came back normal.

I’m just wondering if anyone has had a similar experience and what the outcome was or just any good advice?

(Also didn’t know what group to put this in so if I need to move it to a different one I can. )