Women sometimes do not have many symptoms with having a heart attack. Sometimes they think it's just indigestion or sometimes they just have mild shortness of breath thought to be allergies. The good thing is now that you know, you can take some medication to help prevent future heart attacks.
A heart attack more accurately termed myocarial infarction is heart muscle damage...usually there is heart cell necrosis (dead), but sometimes the heart cells go dormant and with blood /oxygen to the deficit area the cells can be revitalized.
About 5 years ago, I was had had an MI and my first symptom was congested heart failure...I was shocked to hear as I thought my problem was with my lungs!!
A "silent heart attack" is not that uncommon, but the event is more common with diabetics and older individuals. Often heart vessels slowly become occluded and heart cells begin to die causing an impairment of heart wall movement and reduction of left ventricle compliance and pumping functionality.
An EKG is not a very reliable source to diagnose heart cell damage ...false positives are frequent and requires other clinical evidence. An echocardiogram is the test necessary to determine an heart wall impairment.
Do you have symptoms of irregular heartbeats, fainting, light headedness, etc. A holter test would help dx those symptoms, and echo for heart structure analysis, wall dimensions, etc.