Why do I get debilitating ectopics when sitting down

[Prettyfish11]

I am a 58 year old female and I have had palpatations, ectopics, tachycardia most of my life. I have had all the tests and been told that my heart is healthy and it is emotionally caused. I do take a beta blocker. I have noticed that stress is a big trigger and recently I started a new job. After a stressful day I am finding that I am fine when I'm up and busy but the minute I sit down I get really scary skipped beats that run together. They are very uncomfortable and I feel pressure in my chest that almost debilitates me. Everytime it happens I feel like I should be calling 911 but I don't because my cardiologist has told me that my heart is fine. Can anyone relate to this type of ectopic beats?