I went in for my first ultrasound and the said the sac measured 5 weeks , no baby, which is normal for that length of time however based on my lmp I should be nearly 10 weeks along. The doctor said it is possible that I just missed a period before getting pregnant but I have very regular cycles, the first week of every month. And I started having symptoms 7/8 weeks ago. I'm wondering what all of the possibilities are.