Wow! You found the right doc! You may want to ask about whether he thinks nebulizing sodium solution would help get the mucus out. When my congestion from asthma/bronchiectasis is bad, it is very helpful to do before I walk or exercise.
My spirometry results are always "within normal range" but it doesn't stop me from being short of breath when the mucus builds up. Another thing to discuss, especially as cold and flu season approaches, is whether using Mucinex LA (12 hour guaifenesin) twice a day would help. It is a mucolytic, and thins the mucus to make it easier to get rid of.

I am glad you are improving, Sue