Should I worry about my heart at age 28? Normal ekgs (just shows fast heartrate), normal echo shows normal function, stress test good, blood work good?

Exercise ; eat well. Sounds like your heart is in good shape from your tests. Prevention is always the best. Exercise regularly and eat a healthy diet (low fat, low cholesterol) to prevent any heart problems in the future. Some people have heart attacks at an early age. Genetics, poor diet, and lack of exercise often play a role.
Normal data. At 28 with all that normal data, you should avoid smoking, eat a mediterranean diet, get aerobic exercise 30min, minimum daily and enjoy life.........