I Felt A Kind Of Mild Shortness Of Breath, Is It Anxiety Or Heart Attack ?

3 days ago i felt this pushing/heavy feeling on my chest and I felt a kind of mild shortness of breath . I could breath normal but I didn t felt so, this felling has been for as said before 3 days now, it come and go, about 5 times a day I get these mild attacks (almost always when I think about it). It doesn t hurt very at all but it s very worrying and annoying, specially after I read about heart attack symptoms , I felt dizzy and nervous in my stomach and hands. Yesterday I was at the doctor and she took my pulse and blood pressure , the pressure was normal but the pulse was too high because I was nervous. She also listened to my heart and said it was just fine, and I m only 14. In 5 days I m gonna have an EKG test, so it will calm me down. But I can t sleep at night because I m thinking about if it is a heart attack I m having and if 5 days is too late :( none in my family have had a heart attack or heart failure, besides my grandfather but he didn t die, but a lot in my family have had anxiety and nervous heart. PLEASE help, what do you think is wrong?