Potential Twin loss- need advice


I just found out we are having identical twins. The 6 weeks (4 days) ultrasound the doc only saw one and we thought there may have been a heartbeat. We scheduled another ultrasound yesterday and the doc saw movement but not where the heartbeat would be. We later found out I’m having twins and instead of measuring 8 weeks 6 days for what the doc thought was one the two are measuring at 7 wks 5 days. I’m scheduled for another ultrasound next week but the doctor is not optimistic. I’m at a loss. I go from feeling hopeful and completely defeated and just want this pain to end. Any thoughts?

Sorry if this is in the wrong group.