A little back story: my fiancé and I have been together for 7 years. We've tried on and off for 5 years to get pregnant. Consistently for the last 2 years. Last November we found out we were pregnant and at 9 weeks I spontaneously had a miscarriage. We found out recently (the exact same day as last year) that we are pregnant again! Yay! 
I have two children from a previous relationship and had two preterm deliveries. Preeclampsia with one. And now a miscarriage in my medical history. So I'm considered high risk. 
The problem: I was sent for an ultrasound at what was believed to be 6 weeks. They only saw a gestational sac. No yolk sac or fetal pole. I know the dating is a little off because my cycles are not the traditional 28 days. I also have pcos, and my cycles are usually 30-35 days, irregular. So I'm probably closer to 5.5 weeks from my lmp. The doctor immediately started talking about miscarriage and scheduled me for a f/u ultrasound in a week. I am terrified they they won't find anything and that I am in fact having another miscarriage.
The question: has anyone else had this happen to them? And if so what was the outcome? Any advice is helpful. This feels like it's going to be the longest week of my life.