As remar has correctly stated, anxiety does NOT cause enlargement of the heart. An ECG will show abnormalties that could indicate enlargement, but yours came back negative and were told that "everything is OK." So, it's all good with the exception of your anxiety. I agree with remar that you should talk to your doctor about these symptoms as they relate to anxiety. Getting into therapy, perhpas in conjunction with medication, will ease your symptoms and lead you to the source of that anxiety so you can deal with it.
Peace
Greenlydia
I've never heard of heart enlargement being caused from anxiety. The best thing to do is see your Dr for a check up. Sorry I could'nt be of more help but, I do think heart enlargement is caused from other medical conditions, not anxiety. Now, the symptoms you're having are anxiety symptoms. See your Dr for your own peace of mind. Are you in counseling or taking any meds for the anxiety?