33 with lung age 58 COPD

I suffered a bout or breathlessness around 3 years ago when I was a tobacco and pot smoker - was told at the time (I was 48) that I had the lungs of an 85 year ‎old. My mum also had asthma. Despite this, I have only had 2 exacerbations in 3 years that I think were due to smoking a mixture of tobacco and dope - I play tennis regularly, work doing a lot of lifting and walk a lot. No issues climbing stairs. In fact recently scaled the Monument in London without any issues. I have recently stopped smoking pot completely and stopped taking any medication. And in the past 2 weeks have not had any issues. Mainly stopped as I am concerned about possible side effects of the forstair inhaler. Recently saw the nurse at the copd clinic and she said there had been no change in my lungs in the past 3 years. I would appreciate any views on this as I can't understand why I do not seem to have any major issues with mobility unless I suffer from asthma and not copd. Also, the ventolin inhaler did work when I smoked, but don't use it at present as don't need to. Is the GP surgery just trying to scare me? Would appreciate any views.