Are you taking anything to control the panic attacks? Palpitations (skipped beats) and PVC's are not uncommon and I'll bet if the conditions are right, a panic attack could bring them about. Adrenaline is released during a panic attack and can speed up the heart.
I wish that I could explain what all an EKG can determine, but I cannot. You can do a search and get lots of info. They can sometimes tell if you have had a previous heart attack. They can show possible abnormalities related to arrythmias, enlarged sections of the heart, possible cardiomyopathy and problems with the 4 valves of the heart. Lots more also, I am sure.
A 12 lead EKG is the best, I think. Were any of yours of the 12 lead type? If not, then I would get one. If sensors were not attached to your legs, it wasn't a 12 lead EKG. EKG's are only as good as the equipment and the people who perform them, and the doctors that interpret them.
You may want to get an echocardiogram done. I would, if I were you. They are painless and no radioactive contrast dye is used (I think). I know that they are painless. This test is very good in looking into the heart for abnormal valve disorders, wall motion, calculating an ejection fraction (EF), and more. You may have to exaggerate your symptoms somewhat to get the doc to order the test. Whatever it takes, right? I think you may not have to exaggerate any at all, from what you have stated. Just wanted you to be prepared, lol.
Getting dizzy while having PVC's or palpitations is not a good sign. Make the doctors listen to you. Age has nothing to do with heart disease, just the statistics of who has heart disease. Doctors rely on statistics too much, I think.
My wife has taught elementary school for many years. I can certainly understand your stress. Hope you get this figured out and taken care of