You are healing though, I think I read the moment you quit, your body activates that recovery mode, and you should be able to get back to mostly healthy lungs someday.
I also think @soitgoes, that it doesn’t take 15 years to get back to a normal functioning or cleared of the damage.
I’d have to read more on it, but you are young, and maybe have smoked 10 years, so, I’d say you’re looking at the ballpark of about 5 to 7 years. But what do I know.