I'm 18 weeks pregnant according to my LMP, but my ultrasound says I'm 2 weeks more? Confused?

I'm 18 weeks pregnant according to my LMP, but my ultrasound says I'm 2 weeks more? Confused?
Question by cvhgj: I'm 18 weeks pregnant according to my LMP, but my ultrasound says I'm 2 weeks more? Confused?
Well, my last period was November 20th, 2010 and when I didn't receive my period by December 17th (I was a day late) I found out I was indeed pregnant! If the doctors go by my last period, I'm 18 weeks 1 day today and due on August 27th, 2011. The last two basic ultrasounds I had, by two

18 weeks pregnant