Same to me. I was told 12 week according o lmp but at ultrasound I was only 10 weeks its very normal no worries:)
It happens I was supposed to be 10 weeks when I went in for my first doctors visit. But in fact was only 8 weeks. Cycles can be off. Especially if you we're previously on the pill. Your body still might have been trying to get back on track when you got pregnant.