I suggest you to still wait for a week and you can repeat your ultrasound
after a week to visualize the heart beat.
Sometimes the growth of the baby is slow compared to the period of pregnancy
you think you are in.
If you do not see the fetal heart in next ultrasound or have any signs of non viability like regression of gestational sac
of baby , or no increase in size of gestational sac, then the likelihood of missed abortion
increases. In this case you can wait for bleeding to start on its own. Bleeding generally starts within 3-5 days. If not then you can go for a medical or surgical abortion.