low oxygon levels with exercising

dear doctor, im only 32 years old,female ,non smoker and have been diagnosed with emphysema. ive smoked in the past but never many or regulary. i dont have alpha 1 defiencey either.as far as i know my  lungs dont look too bad on x rays but when i had lung function tests my walking test show my oxygon levels drop to 71% the other tests were only slightly low/more or less within normal range. wasnt really concerned at the time when i was told but now after reading up on this im am slighly worried,i dont want to end up on oxygon at my age !! i do get a heavy chest and short of breath a little when active and during night i feel i dont get enough air. at rest my levels were normal...i think.i often have chest pain ,usually left sided. ive been given inhalers and having another lung function in 3 months. should i be worried? and do you think emphysema is  right diagnoses for me? and for what reasons would my levels drop like this?
thank you x

[hlsf]

I think perhaps you should get a CT scan of your chest which would show much more detail on what your lungs really look like as far as problems.  And then the diagnosis can really begin.  Good luck and let me know how things go.  Also, usually when you have a lung problem, they get an idea about everything after following you for a year, so be patient and keep on top of things.  You are responsible for your own life so keep on it.  Also, remember numbers on these test dont mean a whole lot.  Everyone is individual and comes out different.  And you have age on your side in this case.