"But I don't see how there's any way HCG levels this low could result in a healthy pregnancy right???"
"Could it be ectopic??? She had AF like bleeding at first, but nothing now."
I'm not a dr. but I doubt that at this point however, anything is possible. At 6 wks they should be able to tell either way and just in case it IS ectopic, it needs to be dealt with sooner rather than later. I once had a board buddy whose hcg took 2 or 3 mths to return to normal and it was under 10 at that point. I don't remember the exact number. Still, she was getting tested regularly as it depended on her starting her next cycle.
"Does she have to be bleeding in order for her hcg numbers to be decreasing???"
No. As well, no bleeding doesn't mean that hcg won't go down. It depends on what her hormones are doing. She should be getting P4 tested at the same time as hcg. She needs to getting some direction/advice from her health care provider.