Welcome to the board. I'm sure that people will be posting in response to your post and you will see that others are very understanding and wish to be helpful.
I am not an MD, but I'm wondering what your physicians are saying about how your sinus tachycardia might be affecting your level of anxiety. It would seem to me that having something like this is quite upsetting and would lead to higher levels of anxiety. This, in turn, would cause the problems which you appear to be experiencing and that is quite understandable.
You've not indicated that anyone has provided anything in the way of either a therapeutic intervention in terms of cognitive therapy or suggestions about anything else. How about trying some self-help techniques?
Take a look at our Tips column, view the relaxation breathing video tutorial we have there and begin doing this exercise on a daily basis, several times a day. The thing that you want to do is not only to help yourself calm down, but to keep your anxiety level where it is manageable. I think that right now it is at a point where you are feeling it is disrupting your life in many ways and you need some help. This technique can be very effective and I would suggest that you begin to do it along with some self-talk where you reassure yourself that you will be okay.
You've had all the tests that would seem to be required to rule out a physical problem, but I can understand that you have a continuing concern regarding your health. You will get this under control. Another thing that you will want to consider is either some cognitive therapy with a psychologist, lifestyle changes and some mild exercise on a regular basis. We also have exercises that are simple to do in our Tips column. Watch the videos and do the exercises perhaps 2 to 3 times a week if your physicians indicate this is okay.
I hope that some of this information is helpful to you and that you feel much better very soon.
Dr. Farrell