I have to agree with specialmom- unless there is some medical reason not to wait, I would wait it out a few weeks and follow up with another ultrasound- it would give me much more peace of mind to be a little more confident in the dates before I did anything.
I'm so sorry you are going through this- it is so hard to have so many unanswered questions and to be having to make decisions like this, please let us know if we can answer any other questions and keep us updated on how you are doing.
Ugh, I'm really sorry to hear this. But it is definitely confusing with rising hcg levels. And so high! Any way your dating could be off and you conceived later than you thought? This would explain not seeing anything in the sac. The other possibility but your doctor would probably have talked to you about it is a molar pregnancy (which is not a viable pregnancy, unfortunately). Ugh, otherwise, they should be able to see a baby by this point. Unless it could be harmful to you, I think I'd personally wait a few extra days for the D&C to be sure in your heart. I'm so sorry. Please let us know what happens!