I am in your boat. I have palpitations off on and on all day. My resting rate is 110. It is worse for me when I wake in the morning (it was 121 this morning) and after I eat. I was diagnosed with inappropriate sinus tachycardia and orthostatic low blood pressure (I had an events monitor and had the tilt table test done). I feel like crap 24/7 - dizzy, nauseaus, tired, faint, etc.
I also suffer from anxiety - or who knows, it could have been my heart all along. It started about 2 years ago and I was put on an anti-anxiety medication. It helps my anxiety, but not my blood pressure or palpitations.
My cardiologist put me on a beta blocker (I am very sensitive to drugs). I think it was the same one you are on. Within a week my heart rate started to go down, but my blood pressure went down also, so I felt even worse. My blood pressure is usually 80's/50's so when it went down it was terrible. I am no longer on the beta blocker. I am now on a drug called Florinef which is supposed to help my body retain sodium and therefore increase my blood pressure. I have been on it for a week and still feel awful.
I wish I had some success story for you, however, I feel just as terrible as you do. I hope you feel better.