Hi,
I feel your frustration I really do. It seems like you have been dealt a really rotten hand and all of us have times when we feel like enough is enough.
We arent giving up on you here, take some time to re group and re focus - I had to do the same when the drs started telling me that my symptoms including breathing problems - for which I have home oxygen for - were in my head.
Some of your symptoms do sound crazily similar to my own, my sisters and quite a few people I have met on Dinet - the forum and info site I told you about earlier. The problem is many cardiologists do not understand POTS however the site does have a list of Drs who do get it.
Please dont give up
Gentle hugs
Rach