Hello~I am so sorry you are experiencing these issues with your heart.
To be honest, it all sounds anxiety-related. You see, even if we don't think we are nervous, our sub-conscious knows we are, then, when we feel that horrible little "blips", that starts the panic in motion, this in turn starts the rush of adrenaline which makes the heart do the disco dance. The more we worry, the worse it gets. Even if we are a wee bit apprehensive, our bodies are uptight, and this sets up the adrenaline, thus causing the dang skips and fast heart rate. Oh, and even if they did come three in a row, that is not serious, many people have many many more than that and their hearts are in fine shape.
I think all your issues are directly related to fear over your heart (I am that way too)and listening and watching for every little weird feeling and beat.
Try to believe your doctor, I know it is difficult at times, but since all the tests came back favorably and he said not to worry, try to relax and continue on with what you are doing.
I would not worry too much, when ever I wore those monitors, my heart never acted up, why, because we feel secure, thus our bodies are in calm mode. The minute I would return the monitor back to the clinic, however, my darn heart would start to act up again, it never fails. I have heard the same from many other skip-beat sufferers as well.