Ultrasound

I don’t know what to think right now. I’m supposed to be exactly 7 weeks today and had an appointment to get an ultrasound done to hear the heartbeat, but there was no heartbeat. Last week they saw the yolk sac but no fetal pole or heartbeat. Today, now theres a fetal pole but still no heartbeat. Dr said it has progressed but will need another week appt to see if their is a heartbeat. He said to stay positive and this can happen to continue my progesterone..And now it seems like my delivery date moved from Dec 3 to the 17th… what does this mean? Is there any hope? How to stay positive? 💔💔