Right after I got the PFT results from hospital, I bought a spirometer and start tracking my numbers. The numbers started with the same result as what I got from the hospital (FEV1: 3.8L, FVC: 5.73L), and keep a steady growth during the last 40 days, now it's FEV1: 4.38L, FVC: 5.6L. Finally I'm getting a ratio >LLN. Although I'm still suffering from SOB sometimes (not directly related to exertion), but this is what I can see from the numbers.
One thing I found very interesting is, if I use my full force to push the air out, the numbers are worse than I use 50% of the force (FEV1: 4.2L/s vs 4.3L/s; FEF25: 69% vs 83%; FEF50: 71% vs 80%, other data are same), and the curve shows no dent when I use medium force in the test.
And this is aligned with my experience. I get no wheeze and no resistance while exhaling slower.
I guess what's happening is, the airways collapse given enough force while keep opening if the force is below its limitation. There is a sweet spot of the force that gives me best FEV1. So, can I rely on this good number?