I know it’s easier said than done but try to relax, I’ve had heart palpitations multiple times a day for 3 years and have been to the doctors multiple times to get the same response you did, that it’s anxiety. But I’ve been forcing myself to believe it’s only anxiety and nothings wrong and now I’ve had like 3 in the last week. And if it’s helpful, my hands go like that too, I don’t think it’s anxiety though I think it’s to do with the blood circulation in cold environments. Trust your gut if you actually think something is wrong but Sometimes anxiety can overrule how severe your perception is. I hope everything is okay! X