I am 31 yrs old had EKG done it was perfect but have some left arm pain could that be a heart attack?

Not likely. It is my understanding that in an otherwise healthy 31-year-old, a heart attack is extremely unlikely, and left arm pain at your age is probably from some other cause. It is possible, however, for a heart attack to occur in women with a normal ekg; and sometimes it is necessary to get cardiac enzymes and an echo cardiogram with nasal leads to rule out heart difficulties.
Only your dr knows. It's good that your ekg is normal. However, women tend to present differently than men, meaning they have more subtle findings oftentimes, and don't have the traditional elephant-sitting-on-the-chest syndrome. Many women are sent home from the er, only to have the heart attacks occur at home. So, make sure that your doctor is aware of your concerns, and rule out it being musculoskeletal too.