First U/S yesterday, but only the yolk sac

They estimate me to be around 6 weeks today, but could be a little earlier. We didn't get to see the baby yet, just the yolk sac. Next appt is July 7th and he said we'd see the heart beat and baby. He did say that I ovulated twice(was on clomid), but does think I only have one baby in there at this point. I hate waiting!! Lol. I'm guessing only seeing the yolk sac at this point is normal?