Diagnosis, symptoms, oxygen level

I was diagnosed with COPD and asthma after an x-ray two days ago. Is it normal to diagnose COPD before having the pulmonary function test?

I suffer from shortness of breath; however, I also suffer from palpitations and tachycardia (24/7 since last July). I have been diagnosed with vitamin deficiencies which can cause these symptoms. I am also seeing a cardiologist to test for POTS which can also cause these symptoms, though my heart is structurally fine.

I've tried using an inhaler as I do have a history of chronic bronchiits but it doesn't help the shortness of breath so I'm a little uncertain of that being the problem at this time. I'm able to inhale deeply which I can never do when I have bronchitis.

My oxygen levels are 100%. Is it normal to have such high levels if you have COPD? Even feeling my absolute worst, they haven't gone below 97%.

I'm trying to get a handle of everything. Thank you.