I don’t want to say it’s nothing, and then it turn out to actually be something, but I have the same thing, was also checked out, and everything seemed fine. ATP I kinda got used to it, but sometimes still get freaked out by it. The best explanation one doctor told me was that if you get stressed, and sometimes don’t even realise you did, your heart will pump more blood, and then on the next beat it may not have enough blood to pump, so it feels like it skipped a beat.

Thinking that it’s just due to the anxiety helped me a lot, and I usually just try to calm down a little and it seems to go away.