Clear ECGs... still having panic attacks!

So in what has to be the most unexpected hospital visit in the history of the world (in anxiety terms anyway!) I just found myself in A&E while asking at a local pharmacy about the fact I couldn't feel my heartbeat through my chest. Their staff advised me to go to the local hospital to rule out heart problems, especially since I was getting a few ectopic beats.

A stressful afternoon of "what if" thoughts later, and I got an ECG report claiming I'm perfectly fine. However my chest is still tight, it hurts between the ribs in the centre, my back is aching and my heart still feels weak considering how anxious I still am. I just can't drill into my head that a dozen medical professionals have figured out my symptoms - I am certain there's still something wrong, it's horrible.

How reliable are ECGs? Do I have anything to worry about concerning my heart rate and other symptoms? :(

ECGs are very reliable. The symptoms you describe are all typical of anxiety. If all those health professionals have told you nothing's wrong, there probably isn't.
Try relaxing your body, even if you can't relax your mind, there's lots of ways to do this.