Years ago i also thought my fvc was my fev1. I didnt start doing pfts' till i was in my mid to late 20's. ( I have no idea why no-one ever had me doing them before ) When i first got cepacia my pft's were great and when i got sick and reviewed the numbers with my Nurse one day i said, well they are still in the 70's or 80's whatever it was at the time and she told me that isnt the number they look at, she then explained it to me and i was so upset that all this time i thought i had great pfts and a lot of leeway and i didnt. I know exactly how you are feeling