your level should still be doubling, I would get another ultrsound and levels checked again... I had the same thing when I was pregnant the first time and I miscarried due to a blighted ovum... Hopefully u dnt have the same thing... will have u in my prayers.. keep us updated
If they are dropping that is not a good sign. Usually by 8 weeks they will level out but not really drop. Also, by 8 weeks you should be able to see the heartbeat. Has your doctor done an internal ultrasound to listen to the heartbeat?
HCG levels double every 2-3 days from day one up until about 8-10 weeks of pregnancy then level off or do not increase at that rate because the placenta takes over hormone production. Levels dropping, not rising appropiately, or them rising too much could be an indicate a problem with the pregnancy. Also, I replied to your other post about the ultrasound. Sorry about all the worry you are experiencing hope everything works out.