how to test for refractory MAC if can't produce sputum samples

I'm approaching 6 months after starting the big 3 to treat MAC and want to safely and accurately determine the status of my infection. I was diagnosed via bronchoscopy and have never generated a positive sputum sample on my own. Each month since starting drug therapy, I've submitted a sputum sample. My samples are mostly saliva, even after going to the sputum induction lab. Even if I found a way to submit better quality sputum samples, bronchiectasis primarily affects two of my lobes and no one knows whether that sputum came from a part of my lungs that's impacted by MAC.

At the 6 month mark, should I get a CT scan and a bronchoscopy without biopsy? What CT results would indicate the antibiotics are effective? In 6 months, would effective therapy result in obvious improvement in nodules and tree-in-bud opacities? Or would a CT that looks the same as the baseline indicate that the drugs are effective?

I've heard multiple people say they only produced negative sputum samples but tested positive via bronchoscopy. On the other hand, there are risks associated with a bronchoscopy with lavage. Has anyone experienced issues after a bronchoscopy without biopsy? If you're more familiar with the risks involved in bronchoscopy with lavage, I'd appreciate learning more about that.