I've had two mc both at 10/11 weeks, the second just a few weeks ago. After an emotional rollercoaster and lots of scans with the first, in fact very similar situation to yours, I decided to have just one early scan at just less than 7 weeks when I found out I was pregnant a second time - I saw the heartbeat at that scan and because I felt really pregnant I was happy.
At a chance medical apt at 10 weeks I was offered another scan, but unfortunately like you could see nothing only the sac. I was really shocked as had very strong morning sickness and other preganancy symptoms which had falsely given me hope that all was ok. I said I couldn't wait a week for another scan as with my first mc it was agony waiting, so I went back 4 days later where I was told the sac had grown even more. It sounds like your situation too, the sac was the size it should have been at that stage in the pregnancy its just there was no fetus. I was confident that there was nothing there as I knew in my heart there should have been a visible fetus/heartbeat at almost 11 weeks, but if you are in any doubt and need more reassurance I would advise you to request another scan before your D&C.
I'm so sorry for your loss - I can sympathise with what you are going through. I've had two D&C's and to reassure you the operation will not be as bad as you think and from a physical point is relatively painless in most cases. I wish you luck xx