Thanks, everyone, for the reassuring posts. I feel much better. I was talking to my husband about it this morning. He reminded me that they said I would be 8 weeks at our initial appt. that was set for 3/21. I had to change our first appt. to 3/18 due to a scheduling conflict. So when we went in on 3/18, I should have been 7w4d. The baby measured 7w0d. Only off by four days, not seven like I had been worrying about. Since my period was screwed up in January (came a week late) maybe that screwed up my ovulation in February. Or maybe I just have a slightly smaller than average baby. I need to stop worrying though because worrying and stressing ain't gonna help my lil' bean any.
Thanks again for all the caring posts.