I can appreciate that increased problems with your breathing could be very worrisome. But allow me to first put your mind at ease. The chances of your having COPD or lung cancer at age 21 are practically nil. You should have a chest X-ray to rule out any type of previously unsuspected lung disease in addition to asthma. And, since less than 2% of individuals with COPD have it on the basis of inheritance, you might speak to your doctor about getting a blood test for what is called Alpha-1 antitrypsin deficiency.
Also be assured that it is not uncommon for persons with asthma to have a very long recovery period, following just about any type of respiratory infection, viral or bacterial.
As for smoking cigarettes, I would only suggest that you continue to actively work-on smoking cessation. Even if the only respiratory problem you have is asthma, quitting smoking now or in the near future could save you a lot of grief, in the years to come.
Finally, be “religious” about taking your asthma meds and stringently avoid any and all irritants and allergens in your home, workplace or school.
Good luck
I'm also curious about this, I have asthma but my FEV1 even on dulera/singulair on the PFT blowing out with some effort is never higher than the low 70s