You poor thing - I know precisely what you're going through, as I spent years going through it too. Hopefully I can reassure you just a touch.
OK - I started getting skipped beats when I was pregnant 18 years ago. It was like a thump in my chest followed by a flutter in my neck. Sometimes just one - sometimes a run of three or four. It was a daily event.
I was terrified and saw the GP who gave me an ECG. Results came back normal & I was temporarily reassured - but the thumps kept happening and felt serious so I continued being terrified. I could not believe a healthy heart would do this. Surely anything affecting the heart is serious, right?
I also thought I'd end up having a heart attack, or that the rhythm would go so haywire one day that I'd drop dead. I got loads of reassurance, but could never be quite convinced that that there wasn't something seriously wrong with my heart and the doctors weren't taking it seriously enough.
I am no longer in that scary place though because I have finally come to realise that the simple fact of the matter is that healthy hearts DO do this all the time, in everybody. A skipped beat (ectopic beat as it's known) is a variation of normal - but it is normal. It is not indicative of malfunction & does not mean that you are at risk of a heart attack. Not only does it not cause heart attacks - it CAN'T cause them.
I still get them all the time but I don't care anymore - I get them when I lie down on my side at night, and I know when my period is coming because they increase in frequency. I'd rather they didn't happen, of course, but since they cannot possibly hurt me, they are nothing more than a mild annoyance a bit like hiccups.
If you go to any anxiety forum you can see that these skipped beats are universally experienced by people with anxiety (all that adreneline rushing around in anxious people is probably why we "feel" them more than the average person does) - and are also universally the cause of a great deal of fear. It will reassure you to read other people's experiences of this - it helped me a lot.
HERE'S a brilliant article explaining why they are not to be feared. I hope it reassures a little bit & I recommend you read through the forums and see just how common this is.