Sorry you are feeling rough, sometimes it only takes a little time to get that way. Great that you sought medical attention ASAP. As for your question about the Spirometry Test, here is a link to the American Lung Association that does answer that for you, https://www.lung.org/lung-health-diseases/lung-procedures-and-tests/spirometry#:~:text=Spirometry%20is%20the%20most%20common,of%20breath%2C%20or%20a%20cough.
Definitely follow you treatment plan, as for it you start feeling better and wanting to resume normal activity that would be best answered by your doctor. In my personal experience, to many times, as I start feeling better and try to resume normal activity I find that my body truly was not ready and I wear it out and have to start all over again at square one for treatment, prolonging my recovery. Please check with your doctor first. Keep in mind if you are suffering from something other then COPD, such you mentioned bronchitis please wait until that is cleared before doing to much out in public, no sharing allowed LOL .
I personally find mornings and evenings to be a little harder on the breathing for myself. Waking up is the dryness yuks and even it feels as if the air is heavier, I take that for I am tiring out from the days activities and my boxy (lungs) is letting me know it's time to rest.
Allergies! Well that is a fun one to add to the mix. May I suggest that if you feel you are having some sort of allergic reaction via something in the house or even pollens, might be a good time to get allergy testing and a treatment plan for that started. As for my allergies made a huge difference I how I feel and of course can add to lung issues that you already have. If you are aware of what you are already allergic to, then try to avoid them all together if possible.
Check out this whole site, it has tons of information about so many aspects of this disease from beginning to end, learn as much as you can so you can live the best life possible.
Best to you,