I had a normal echocardiogram but a abnormal nuclear stress test. i was told that a abnormal test means you have more than 70% blockages?

Physiologically,: arterial blockages are usually not symptomatic or highly obvious on noninvasive testing until they reach 70%. The abnormal test is wrong (falsely positive) 15% of the time too so you won't know for certain without an invasive test or perhaps very high quality CT angiogram. Discuss these concerns with your health care provider to figure out what your next step should be in your evaluation.