High HCG LEVEL?

Maria
Has anyone had high HCG (6000) at four weeks and then go on to find out your having twins? I had a vaginal ultrasound sound today, dr thought because of HCG levels I was 6-8 weeks but couldn't see fetal pole. I know I didn't conceive this baby until mid February which mean embryo is only like 25 days old. I'm so confused. I hope it's not blighted ovum