Re: concerned about h/b
Molly,I dont know about your midwife but with my second son I had to have several ultrasounds and the first was when I was about 4 weeks pregnant and we saw a heart beat...it was fluttering very fast on the ultrasound but it was there. It actually does start beating after it is formed which is about four weeks though at that time it is only a tubal shaped organ that will fold in on itself and by week six it is the proper shape of a heart.
As for the growth your dates could be off. I know with my first I only knew week I got pregnant so we went through several due dates before we finally figured it out. Though I wound up delivering a week late. With my second I knew the exact date of conception and we had our second the day before his due day.
U/S are pretty good at giving the growth and such. I know with our second every u/s matched up to the dates we had. But there are times where the fetus will either be a slow or fast grower in which the u/s will give inaccurate results. So relax and try not to stress too much because it isnt good for you or the baby. Wait until the next u/s to see what is going on there.