I should also note that my due date according to the ultrasound is Dec 1. This is about 3 weeks - a month difference. Am I worrying for no reason?
I am going to guess that based on the ultrasound that your fiance is in fact the father. I know the ultrasound can be off by a little but I doubt it is off by a whole month. Does your fiance know about the man who forced himself on you? If not you may want to let him in on that tidbit of info. Also, I hope you pressed charges against the guy. No one should ever be allowed to do that and you may not be the only woman he has done that to.
You would not have conceived on the first day of the '6 weeks 1 day' count they gave you, unless you asked SPECIFICALLY for a conception date. You would have conceived about 4 weeks 1 day before an ultrasound that gave you a 6w1d 'gestational age.' They begin the pregnancy count on the first day of your [assumed] last period. Although sometimes the first day of the last period does not wind up fitting the average (because women ovulate at different times in their cycles), you can always take the count given to you by an early ultrasound and remove 14 days, to get to a presumed conception date. That puts your presumed date of ovulation March 10, which is way too late for your molester to be the dad.
Take the start of your last period add 2 weeks give or take about 2 or 3 days and that's how I figured out. But the ultrasound machine or doctor can telll you when you conceived. But don't worry it'll be ok in the end.
Brandy, did you have an ultrasound to confirm? Counting forward from the first day of your last period is not as reliable as computing from the estimated due date given to you by ultrasound, since not all women ovulate at day 14 or 15 or 16 of their cycle. (My sister ovulates at day 8, and I've heard that is not uncommon.) An ultrasound measures the actual baby, and if done early enough in the pregnancy, can be very useful for helping sort out who the baby daddy is.