I have and have had the same sensations. Basically it feels real tight in your chest and you can't get rid of it which is often accompanied by some sharp pains. For me, it's usually around my upper left breast plate near the center of my chest..more towards the surface than it is deep inside my chest. It is sometimes accompanied by weird sensations or pain in my lower left armpit. Sometimes it gets so annoying that I scream inside my head, "If somethings going to happen to me..just do it already!". It gets real frustrating/annoying. I found that if I take some tylenol that it usually helps or some ibuprofen for an anti-inflammatory.
I am assuming you have been checked out by your doctor at some point who has told you that everything is normal. If not, I would get a doctor's opinion as is always a good idea with chest pain. However, from what it sounds like you are just suffering from the same symptoms all of us have, so we are all with you! It's scary and you have no doubt in your mind that something is wrong, but it is really just your head making you feel that way. For me, these symptoms will last a while, but they always go away. I usually like to feel my pulse as well to reassure me that my heart is beating fine and kind of get lost in the rhythm of it.
Like I said, it is always a good idea to get checked out by a doctor if you have not already, but I believe the symptoms of a heart problem are more obvious and are accompanied by vomiting typically.
Hope everything turns out okay.