Confused.

I'm supposed to be 10 weeks 3 days today. That was according to the doctor when I first went. Had my first vaginal ultrasound on friday. GA says 10w2d, but after it was done, my OB said I was further along then she thought being 11 weeks 5 days, today. I'm so confused. And my baby in the ultrasound looks further than 10 weeks..