My echocardiogram and my ecg were normal, so what are the chances of my stress echo being normal if i did the test? high right?

Likely normal: It's likely to be normal but not for the reasons you list. Because you're 24, the incidence of coronary disease is very low, so your test will probably be normal. However it's entirely possible to have a nl resting echo and nl EKG and an abnormal stress echo which is specifically looking for evidence of inadequate circulation. The resting tests are relatively insensitive to that.