5wks 2day no fetal pole visualized is this normal?

When I was 4wks 2days 10/14 my hcg count was 2,672. Two days later 10/16 4wks 4days it went up to 5,068. Three days later 10/19 5wks it increased to 14,369 then I had by Ob appt yesterday and it was just for my bloodwork result but the doctor felt the need to do a ultrasound since I already have had 2 miscarriages in less than a year. A gestional sac was visualized with yolk sac but no fetal pole! Is this normal for my LMP being on 09/15/09 so that makes me as of today 5wks 2days. I'm just so scared that I miscarry again!