Hiya Kathleen,
Like yourself I tick all the boxes as to what may be the problem. My heart often skips a beat (makes me cough to catch my breath) and I am sometimes breathless.
Many years ago I had this checked and was found to have a slight heart murmur. Mine needs no treatment, and will not cause me harm, but I am used to the odd flutter and 'gaps' in the rhythm. I have a ridiculously low pulse too.
I would definitely have a word with your g.p. anything like this that comes out of the blue should be checked. Of course it's likely to be yet another 'just one of those things', but they seem to add up endlessly,.and I do understand this will add to the anxiety.
And stay away from Dr Google! The illnesses I have convinced myself I may have....but we just can't help ourselves. Do get your drs appt set up to investigate. Am sure it is nothing to worry about Kathleen, but best to check. Will put your mind at rest.
Am sure others will be able to send suggestions and their own experiences.
Take care of yourself