I'm sorry to hear about your loss. Did you have any reduction in your pregnancy symptoms? I don't feel as sick today and can't tell if the breast tenderness is less. According to what I read on the internet, the yolk sack should be 5mm. I am going psycho waiting until Friday for the repeat US.... every thing I have read on the internet and other forums did not turn out well.
What size should the yolk sac at this point? I'm not sure what to tell you. The only thing I can say is that if the pregnancy is abnormal the body will try to get it out at some point. I went to the ER today for bleeding. I'm 11 weeks pregnant and started spotting on the 10 week. For mine they saw an empty sac. I should expect a miscarriage. But your case is different. You do have a fetus. Give it time. Everybody's body is different. Maybe the sac would get bigger. I'm guessing is smaller than it should be from what you wrote. You might not loose your baby. As longest there's a heartbeat there's life and hope. If things seemed to be not right with your baby and there's hope, and you are given options by your doctor wait till you hit 12 weeks to make a decision because nature fixes itself. Many pregnancies by 12 weeks start running smoothly. I wish you the best.