Your anxiety could potentially be making it worse. The most definitive way to check for Covid is a PCR test but you really don’t need one if all your tests are coming back negative. Colds and bronchitis can take a bit to get out of your system and if it is bacterial like your doctor said then some relief could come from knowing you know what it is you are facing and there’s medication made for it.
If your doctor thought you had bronchitis, that means he thinks it's a bacterial infection. If you didn't get better after finishing the entire prescription of antibiotics, I think you need to call the doctor to return. Did the doctor test you for covid? If you had it previously, you could have a post secondary infection. But I your doctor didn't give you a covid test when you were there? I would guess that you don't have covid. Also, infections seem to be much less severe than previously. So, you'd likely recover without respiratory symptoms like you describe lingering. Long haul covid is more things like being tired, easily exhausted, and mood issues. So, I'd see your doctor and get them to administer a covid test and go from there. You ay need a stronger antibiotic or for whatever it is you have to work its way out of your system.