2 cm ahead? 34+3 days

Naizsa
Hello. My doctor has told me that I am 2 cm ahead when measuring my uterus. She said if I was 3 cm ahead, they would do an ultrasound to see if baby is growing fast and if change in due date. I'm so confused. 
I'm due nov 6th but thinking sometime in oct is when the baby will come? Is that what she is meaning?