Hi so on my ultrasound I told them my last lmp was October 30 now I don't really remember if that is true.. so on my ultrasound it says that I am 12weeks pregnant if o got pregnant in October would I be able to know from a ultrasound because frm October 30 to January 25 that is 12weeks including the week I was on my period... so do I count the whole 12weeks or count back 10 weeks

When dating a pregnancy, gestational age is most often used. This is taken from your last period. You are not usually actually pregnant at that time, but since most women do not know exactly when they became pregnant, this is what is used. An ultrasound may alter the dates a bit depending on baby's stage of development, but this is not exact either. However, it is generally thought to be closer than by using just the lmp.

If you don't know your lmp, then ultrasound would be used to determine how far along you are.