Please help me

My HCG has increasing how it should, 80 then two days later 800 then almost a week later 8000. I thought I was 6 weeks today. I went in for a transvaginal ultrasound and they saw the gestational sac and the yolk sac inside my uterus but no “baby”. He told me to come back for another one in a week but that it should be visible by now. I feel so lost. Has anybody experienced something similar and it been ok? I had my blood drawn again today, should have results tomorrow. I feel like I can’t breathe. If anybody has any stories of similar situations please share them.