I'm doing really good but I'm scared

My pulmonologist has yet to say. "You have copd." She put it on my chart explaining that the drug she gave me thinking it was asthma didn't reverse it, so....
I cough up a small amount of phlegm at dinnertime after a day of a runny nose. Other than that, little wheezing at bedtime, nothing a cough won't take care of. I can still walk 3 miles when the weather's good.
I'm wondering how many of you realized this early on and any advice on slowing the progression.
I quit smoking 5 years ago