I’m not sure if this pregnancy is going like it should my last period was February 4th. I went to the er on March 10th for cramping and bad pains all they seen was a gestational sac my hcg was 2200 I went to my ob on the 13th and we seen the same just a empty sac. I have another scan tomorrow but I don’t know what to expect. How long does it take a yolk to form after seeing a gestational sac?