Nuclear stress test

I had a heart attack 5 weeks ago. The doctor said it affected 10 to 15 % of my heart. My EF is 55-60%.
I had been exercising for the last 25 years by walking 4 miles 2-3 times a week and using 10 to 15 lb. free weights for the last 15. I have weighed 109 to 112 lbs for the last 20 years. Before that I weighed a couple of pounds less. I have tried to eat well all my life. At my last check up with physician in June 2007, she said I was doing well. My cholesterol was around 220, however, my other lipid numbers were OK and she said they as a whole were good and did not recommend any medication for cholesterol. However, I had been under extreme stress at work, often working 6 days a week and always thinking about work. Can stress alone cause a heart attack?
I had a cardiac cath several hours after the heart attack and since the clot was in small artery I did not get a stent. I was put on heparin for several days. As far as I know the other arteries were OK as I was not told there was any problem with any of them.
This past week I had a nuclear stress test done, but I was on the treadmill for less than 3 or 4 minutes. I did not even get a little out of breath. I don't think my scans after the exercise portion gave a true picture. The technician told me later that the doctor rushes the ones at the end of morning so he can be done with all of them by 12 noon and she feels this is not fair to the patients at the end. We are all called to come in by 9:00 AM and then are there for 3-5 hours according to the instructions they give us. It is done rather in assembly line fashion.
The doctor called me the next day to tell me the results were OK, however, does this test sound as if it was done correctly and fully? All my RN training tells me no (the doctor knows I am a nurse).
I am picking up some other warning signs too and I think I need to find another cardiologist (he was referred to me when I left the hospital) and would like your feedback. Thank you.