Thanks for your question and well done for giving up smoking! Together with excessive alcohol intake, hypertension and poor fitness, smoking is one of the biggest risk factors for health.
The only thing I would add to the excellent answers you have already received, it perhaps consider a CARDIO-PULMONARY EXERCISE TEST (CPET). This is either in the form of a cycle or running test and will essentially allow the physician who is looking after you to assess your physiology. Sometime after you have been a smoker for a while, it might be a respiratory, cardiac or muscle limitation to your capabilities and a CPET can certainly help establish where the limitations lie.
I hope this adds to what you have already found out.
BW
Dr Dinesh
