I have asthma, so I understand the feeling of not getting enough oxygen. Have you ever considered the possibility that you have GERD/reflux? My asthma was made much worse by my reflux until I got it into control. You can have asthma-like symptoms caused by reflux getting into your lungs, which can be damaging.
I suspect that your allergist will be aware of the GERD/asthma connection, so be sure to mention it. You can have silent reflux and not even be aware that it is happening.
Let us know how your appointment goes!