Hi Trina,
Sorry it took so long for me to get to your post. Not sure how I missed it.
I think that it's often the case the doctors will write off palpitations to anxiety because there are so many of us out there that have some level of anxiety and that it can be a causing factor. And sure, it's possible to be anxious 24/7. I've done it.
I think it's great that you've had the important tests and that they've all come back clean. If I had to guess, they put you on the beta blocker because the palps were bothering you, and it was affecting your quality of life. You may find that once you have the courage to ease back into your exercise regimen, and cutting out as much stress as you can, that those palps will start going away, and you'll no longer need the beta blockers.
Please keep us updated as to how you're doing.