Hello Helen @helenrivera You might try Airway Clearance to help bring up the mucous/sputum. For me this includes Nebulizing 7% saline in AM and 3% in PM. Aerobica device 2-3 times throughout the day. Once daily usually late morning I will do postural drainage (you can put that in the search bar at the top of this page and you will find many helpful things to try), then manual percussion on my chest followed by huff coughing then regular coughing and I almost always get up 1-3 tsp of sputum. Luckily I have been off antibiotics for almost 2 years and I have no symptoms other than the cough. My yearly CTs and breathing tests are all stable. I read your history and I see your case is more complicated but I really think the airway clearance will help you. I would invite you to view the following youtube video by Dr McShane.
https://www.youtube.com/watch?v=L-EHohMe7II
Good luck to you, Bill

It sounds like you are doing everything right. Not everyone produces much mucus. My daughter has nearly none unless she has a cold. Unless your lungs are crackling, I don't think I would be too worried.
Have you discussed this with your docs?