You ask: “Has my emphysema worsed to the point that I can't reverse the ill effects or prolong it if I quit now and began exercising and taking better care of myself.”
It is very unlikely that smoking, even heavy smoking for 1 to 1.5 years, would further damage your lungs to the extent, that the benefits of smoking cessation would no longer be available to you, especially at the age of 43. You should make every effort to quit smoking now. If the amount of emphysema on CT scan a year ago truly was minimal, you should definitely be able to preserve good lung function.
CT scanning is an expensive way to quantitate emphysema. You would do well to ask your doctor to order pulmonary function tests (PFTs). This is as good or better a measure of chronic obstructive pulmonary disease (COPD)/emphysema, can be done at one year intervals at minimal expense and provides a good quantitative measure of progression of emphysema.
That you have CT signs of emphysema at age 43 and your mother died of this disease raises the question of alpha-1 antitrypsin deficiency, an inherited disorder that, especially with smoking, leads to rapidly progressive emphysema at an early age. You should ask your doctor to test your blood for this disorder.
Good luck with your smoking cessation efforts, even if only to cut back. Every additional cigarette smoked per day makes a difference.