Ultrasound is at 11:30am today.
We should know more soon.
Update: Ambiguous-to-good news. The ultrasound revealed some development, namely the appearance of a yolk sac, which was absent during the ER ultrasound. The technician couldn't draw a bead on a baby, but that didn't seem to surprise her. According to her, that put development at the 5 weeks, 5 days stage, not the seven and a half weeks we assumed it was.
The ambiguity remains, though--the slow hormone increase, the heavier-than-normal bleeding and other bad signs earlier on, and our calculation of 7.5 weeks. Our ob/gyn could have offered more insight, but she was not there today as her children are sick and she's come down ill herself.
So, the upshot is that we have more hope--and more reason for it--than we have had for a few weeks, but I'm keeping my guard up.