Ultrasound

5w6d today by LMP, went to my OB as I passed a clot and had some bleeding last night but it only lasted an hour or so and had stopped by this morning. I had an ultrasound today and we saw the gestational sac and the yolk sac measuring right at 6 weeks, no baby yet. The ultrasound tech was pleased and said everything looked perfect for where we were, as did the midwife. She said we are literally only a couple days from seeing baby/heartbeat. My HCG was 13,965 today and my progesterone was 24.5. I go back Friday for another ultrasound. However I saw my sons heartbeat measuring 5w5d. That part is making me nervous. Does this sound okay and normal? I am terrified of a blighted ovum.