A premature ventricular contraction or PVC is where the lower pumping chamber of the heart pumps a bit too soon. You usually don't feel that because it is pumping out a slightly lower volume of blood since it did not have time to fill completely. Then there is a pause as the part that sets the timing of the heartbeats resets and that lets the chamber fill with a bit more blood than usual the next time it pumps out. That is when most people feel as a kick or a thud. It is because the chamber is pumping out more blood.
Lots and lots of people have them. Some people feel them and some people don't. It is not a problem if you have a structurally normal heart. That is why most the time the cardiologist does an echo to make sure the heart is indeed structurally normal. Then they say, "Nothing to worry about. Ignore them."
It is no big deal to have PVCs or PACs which occur in the upper chamber rather than the lower chamber. However it can feel uncomfortable and very annoying.
Hang in there! I still think your doctor needs to do more testing to make sure everything is OK.