Possibly going to miscarry

I have had a long hard road trying to conceive. We have been trying for 2 years. Have had a blighted ovum and a chemical within the past year and half. We are pregnant again and it has already been a long stressful, emotional rollercoaster. I went for my first ultrasound expecting to be 7w3d. I was measuring at 6w1d and could only see a yolk sac. So my dr got me to do bloodwork every couple days to check hcg and to have another ultrasound in a week. We were hoping that I possibly ovulated a bit later or implanted later. We went to our second ultrasound and was shown our little nugget and told that they could see a heartbeat but that is all we were told.

My dr called the following day to tell us that the heartrate was quite low. The fetal pole was small and yolk sac was quite large for the stage we should be at. She also told me my hcg levels were 22000, 29000, and 33000. So they are going up but not what they should be. She told me to prepare for a miscarriage because it is looking like the pregnancy wont be viable. I need to keep going for bloodwork and have another ultrasound in a week. Has anybody gone through this and what was the outcome? Any advice would be great! TIA.