Thanks for posting your query.
It is possible that the bleeing that you had, however light it seemed, might have resulted in a miscarriage
. It is not possible that the ultrasonographer who saw a 6 weeks + pregnancy
a week back, should not be able to see anything on a subsequent scan.
If you were not explained anything, I suggest you go back to your doctor, who should explain everything and may do a few tests.
Hope that answers your query.