Miscarriage

I went in for a private scan today and found out I’m going to be miscarrying. I should be 8 weeks 6 days today but the gestational sac is measuring 8 weeks 1 day and it’s empty through abdominal scan. I don’t understand how this could happen again my hcg is 43,212 and at 5 weeks I went in er and had a Transvaginal scan and the fetal pole and yolk sac was there I just don’t understand where it went or why it disappeared but I’m devastated.