To be honest, it doesn't sound like a heart attack. (I know, because I'm a hypochondriac too and I thought I was going to have one once, so I looked up all the symptoms.
Yeah, it's sad, I know.) From all the nice websites I've looked at, the main warning signs of a heart attack seem to be a feeling of extreme breathlessness, like you absolutely cannot breathe no matter how much air you try to gulp into your lungs; a crushing pain in the chest; and dizziness, as well as tingling in your left arm. If you haven't had any of those things, I'd think it was something else. However, if you're worried, go to the doctor--one trip is definitely worth the peace of mind.