Could you have pulmonary embolisms so small that you would never notice? My dr said if it weren't for newer equipment they never would of seen them.

Yes. There are people with chronic small pe's that they only become symptomatic when more areas have been involved as they accumulate. Small clots don't cause much symptoms. If you look at people who go to surgery in the past when did not have the prophylaxis we have now, perhaps, up to 20% had small pe without symptoms and they did well.