Another miscarriage?

It's happening again???!! In June I had a miscarriage ( I went in for my 8 week scan and there was a 4 week sack with nothing in it, a week later I went back and there was no progression) I am pregnant again and I went for an ultrasound today at 7w1d .. they saw a sac that measured 4w6d .. no fetal pole which is normal for a sac that size but I track my periods so I know when I had one last.. I have to go back next week for another ultrasound but I'm not expecting good news. What have I done to deserve this ??? I have no kids and my first two pregnancies seem to be the same type of miscarriage!!! I am just so devastated ... just seems unlikely I'm off by 16 days being that I track my period. This sucks:( just needed to vent.