I share your symptoms. First and foremost, your are not going crazy. Stress and anxiety can cause many physical issues. I have recently being investigating Hiatial Hernias. The symptoms are consistant with yours. Particularly the acid reflux relation. May be worth checking out. For the stress/anxiety, I found a book that really helped me. It is called "A New Earth" by Eckhart Tolle. It is very Zen, but puts everything in perspective. Hope you find some relief,
JPEK
I read you to say you have diagnosed (by a doctor) anxiety. This can be a driver of heart rhythm/rate abnormalities. So, I'd guess that is the source of your heat rhythm concern/problem.
Try to "measure" you heart rhythm/rate when you feel calm, and not anxious and see what it is doing at those times. Sometimes just thinking about the heart rate can affect the rate... so try to be "casual" in thinking when you check you heart.