Freaking out

I had an ultrasound last thursday and we thought I might be around 7 weeks. My a

Period has been all messed up and we honestly weren't sure. They said I was measuring 5 weeks and 6 days. I was supposed to have an appointment at the ob office this morning and they called and cancelled it and said "we found no heartbeat, so either something is wrong or its just too early" I had a silent miscarriage around halloween last year and I am freaking out. I have to go to work all day now with these thoughts. When they tested my hcg levels last week they said they looked great but now I feel so hopeless :(