Could a 15 year old girl have a heart attack?

I'm REALLY scared that I'm going to have a heart attack. The pain is not very severe, but my left arm hurts too, and I've heard that that was a sign of a heart attack. This started a few days ago. I spent a few hours outside, where it was really humid, and I almost ped out, and had heaviness in my breathing. I feel a bit nausea as well, but it feels more like menstrual cramps than virus nausea. I wasn't born with any heart defects, but my family is sort of poor and I haven't had a check up in a long time. Also, I'm a hypochondriac, and a day or two before these symptoms I read this thing about "six signs of an impending heart attack". I told my aunt, and she thinks that my symptoms are psychosomatic. But I can't calm myself down or tell what symptoms are real or not. Is it possible that I'm having a heart attack?