6w 1d sac but no baby and little bleeding

I'm so concerned because I had a miscarriage on May 12, 2017... I had 1 normal period and got pregnant right away. Today I'm 6 week 1 day, got up to pee and there was light blood so I went to my doctor for the second time in a week. At 5 weeks 1 day and at 6 weeks and 1 day they see the sac but no yolk. Doctor said, possibly a miscarriage (blighted ovum) but maybe to soon to tell. . . All I wanna do is cry but in my heart I still feel some hope. I'm not cramping, just a little discomfort. The medical assistant told me to hold on to hope and the doctor told me to expect a miscarriage but to pray for a miracle.