Pregnant, Bleeding. Ultrasound Shows Gestational Sac, No Fetal Heartbeat. Chances Of Survival?

my lmp is 25.05.2012 and i had slight spotting once during this pregnancy and was put on Duphaston tablet twice a day.yesterday(11.07.2012) i had spotting again and the doctor did an ultrasound and found that the CRL measures 5mm corresponding to 6 wk 1 day, but no cardiac activity was visualized. Also the us report says large gestational sac with non viable fetus seen within uterine cavity with mild GS separation/retrochorionic hemorrhage . During my last scan on 05.07.2012, they could see only the sac without fetus and after 5 days, a fetus without heartbeat . Is it possible that the baby is growing slowly?Should I wait for another few days and check for heartbeat again?My doctor has now told me to stop taking duphaston tablet and wait for a natural abortion and if no bleeding comes, to do an us after 10 days. Please help,is there any chance that my baby is still alive inside and will develop heartbeat.