6 weeks and no heart beat or fetal pole

Hey everyone! This is my first time posting on here and am having a hard time. I am 6 weeks 1-2 days pregnant and had an ultrasound done today, due to a past miscarriage last year. They found the yolk sac but no fetal heart beat or fetal pole. My hcg levels have been going up from over 800 to 3500. They rechecked my hcg today and I am praying that it has gone up again. I really do not want to have to go through another miscarriage. Has anyone else been through anything similar?? My anxiety is talking over! Thanks!