Aww-I understand that fear as I'm going through it too
I've found that google does nothing but make my fear worse. There are stories out there of people who have "normal" scans and then end up with stage IV something or other. They scare me, too. BUT...if you were to count up how many of those stories there are, and compare it with the number of people whose normal scans are truly normal, I bet you would find that it is rare to miss something like bc.
Stay off google-especially websites like you mentioned. Those are frightening places to go, and don't do anything to help you out.