was told blighted ovum..

So I just want to know if anyone else has had any experience like this. When I was 5 weeks I had bad back pain and thought it was a kidney infection and went to the ER, so while I was there they did a US just to check on things and said I measured about 5 weeks. The US tech said I have a retroverted uterus so it was hard to tell, but that he could see the fetal pole while doing the US, but the doctor came in and told me that it looked like a blighted ovum and that I was probably miscarrying. Well, now I am about to be 12 weeks and I have not miscarried. I have an US in a few days and am just nervous on what's really going on. Anybody experience anything like this?