has your baby measured bigger in 1st trimester?

Meri
I just had my first ultrasound at 11+6. baby looked great with a strong heartbeat but was measuring at 13+1. we were blown away. I used the symptothermo method so I know with high accuracy the date I ovulated and my husband travels a lot for work and was only around for a few days prior to ovulation so there's not a lot of wiggle room on the conception date. 
anyway, has anyone else's baby measured over a week ahead in the first trimester? I've read over and over again that all babies are the same size at this stage so Im just curious about other women's experiences.