This is tricky. If your PFTs results were in the high
normalNormal saline flush range that would be definitive proof that you do not have chronic
obstructiveAcute bilateral obstructive uropathy
Obstructive uropathy pulmonary disease (COPD) or emphysema. If the results were "normal" or borderline, and at one time in the past were high normal, it is conceivable that you could have early COPD and still be declared to have normal PFTs. Lungs that are a "little large" is a very soft finding. Large lungs can also be seen with sub-optimally controlled asthma.
Bottom line – you cannot have "great PFT readings" and still have COPD. The x-ray is an insensitive way to make the diagnosis.
Congratulations on your intent to stop smoking. As the American Lung Association says, "It is a death-defying act."