Possible blighted ovum

Today I went in for my first US and from my calculations I am supposed to be 7 weeks, 6 days. I was so anxious because my pregnancy prior to my youngest child I have now was a blighted ovum. Sure enough, I go in and they can only see a gestational sac & a yolk sac. She could not find a fetal pole and I am measuring at 6 weeks and so many days. She said that this could possibly be due to my ovulation date being off from what I thought it was, but I am not very hopeful. I am trying to stay positive, I go back for another US in a week to check things out again, but I cannot help but feel like this is happening all over again. ;( I wish she would have checked my hCg level also but she did not do that like last time. Please, any prayers would be appreciated.