Once you get an ultrasound you'll know the dates better when we were trying to figure out the date of mine we were a week off, I wouldn't worry to much about it :)
I am also at 5 wks now, but when I got my results back from the blood test they were a week ahead ... dont know if that helps or not, but you should be able to go for an ultra sound and another blood test n they should be able to tell you for sure
Thank you so much... these comments help....