Re: don't know what to think
For your own peace of mind, I would suggest requesting a genetic blood test. DS passed his sweat test with flying colors --- a normal 32, so not even borderline. So for months in the back of my mind, I kept thinking that the doctors were wrong that he didn't have CF. Even though a blood test taken by another doctor showed otherwise.
Could be that your son, if he does have CF, has a mutation that has milder symptoms -- maybe not so much pancreatic issues, but lung issues that show up more as asthma. There are lots of CFers who aren't diagnosed until they're adults.