Ok, I will keep this as short as I can. Basically I haven't had a period since December 26, 2006. It was confirmed on March 1st that I was pregnant and that now I am supposed to be at 12 weeks pregnant. But when I went yesterday for my first sonogram, the doctor (based on the size) said I am only at about 5 weeks along. I tried to comprehend how this could be, but every time I think about it I can never see how three months of missed periods can only make me 5 weeks pregnant. My periods have always been on time and scheduled ever since I started having them. Please help explain how this could be because I am confused. Thank you!

if your last period was december 26, then you probably got pregnant around the middle of January which would make you 5-8 weeks pregnant depending on the exact date..