During college, i had bouts of coughing up lots of sputum, lasted about 2 years. no symptoms since. could it have cause bronchial damage? never smoked

Sure, but.....: 1) without an exam, I can only give general information and cannot say in your particular case and 2) you don't have the problem now Infection/asthma/allergens can cause a temproary lung inflammation with asthma-like symptoms and sputum. Often it goes away. It is called "reversible lung disease" for the reason, it often can completley go away.

Depends....: It depends on the reason for the abnormal sputum production. The best way to measure your pulmonary function is to do a pulmonary function test. This could show if there is any problem with your lung function. A high resolution CT scan can show what your lungs look like. The 2 tests together can give a good idea of the amount of damage, if any, in your lungs so see your doctor ASAP!