A "PVC" is an electrically defined phenomena. It is not surprising you did not develop one while simply taking an EKG. A stress test with EKG is generally required. A radioactive substance with a stimulant is injected intraveously while the heart is imaged.
In an of themselves PVC's are not harmful. If they take place at the wrong point in the pumping cycle they can precipitate ventricular fibrillation, but this is not common. For various reasons some people have heart muscle that is more sensitive to this kind of activity. Caffeine increases the propensity. As stated, they are usually benign.
There are "missing pieces" to your preoccupation with your heart.
Clearly, this was not a thorough cardiac evaluation. "Listening" and an EKG alone don't pass the smell test. Giving your M.D. the benefit of the doubt he/she probably just wanted to make you feel better.
On the other hand unnecessary medical tests are another problem.
You are wise to think twice about taking a beta-blocker. It interferes with the ability of the heart to compensate to a sudden requirement for additional circulation.
You might want to think about getting a second opinion from an M.D. who runs a full schedule of tests.
PVCs, SVTs, etc are very annoying and unnerving, but in most cases benign. More a nuisance than a worry. The beta blocker may give some relief in that its use is to diminish the effects of stress hormones. It is also effective in lowering blood pressure. An echo 5 years ago is a stretch. If the doctor feels it is necessary, it would certainly need to be repeated after that long. EKGs aren't very reliable in my opinion. With both of my heart attacks my baseline EKG was for the most part normal. It did show that I was having SVTs. The queasy feeling may be from the unsettling way the PVCs make you feel. Just my thought on this.