Could my due date be wrong?

Hannah

Before my first ultrasound I calculated my due date as 27th March, my periods and ovulation were like clockwork and I could tell you the exact day she was conceived.

At my first ultrasound they set my due date back to 8th April (2 weeks back), but now my little girl is measuring 2 weeks ahead on ultrasounds and my uterus is measuring 2 weeks ahead too. She's also head down, engaged, and in anterior position so, as my midwife said, "ready for lift off!"

Could it be possible that the due date I initially calculated is correct and that maybe she was just measuring a little small to start with, but has now caught up?