I will just tell you what happened to me. I went in almost 4 weeks ago, My level started at 840--740--1130-1440. that drop and the fact that they did not double was a pretty good indicator that things were not going as expected. I have been on the roller coaster since there is always a chance things will be OK. U/S will definatly show you what is going on. Last week the baby sac was measuring 5W5D, yesterday it measured the same, at almost 8 weeks no fetal pole, no heartbeat, I am pretty much growing an empty sac. So I will be going in for a D&C in one week, giving time for my body to MC on its own but i don't want to drag this out. The entire time I have felt totally fine, just fatigued. No bleeding, no cramping. So it is really hard to tell. But for the last 4 weeks I have treated myself as pregnant and gave it the appropriate amount of time for the Doctor to be positive. Good Luck and I really hope none of this scared, afterall every women is different, I just know real stories can help.
I too was at about 5.5 weeks I found out I was pregnant at 3.5 weeks (very early). Unfortunately I had somewhat of the same issue. My levels were around 70 and dropped to around 20, and was considered a miscarriage. Like Sheaby said it doesn't sound very hopeful, but all you can do is wait it out to see. Your Dr would be the one to give you the best advice on it since they will know a lot about you and possibitlities. If you need a friend or anyone to talk to we are here for you. Take care of yourself, and anything can happen considering a person's body is full of mystery.
It doesn't sound very hopeful. I've seen some rare cases where the hcg dropped then rose back up again - but it doesn't happen often. The problem with us TTC'ers is that we test so early, we are liable to catch the m/c, where as most people miss it because they don't know yet to even test. With your hcg results only rising 12 miu in 2 days, that isn't a good sign. I'm so sorry you are going through this. A lot of us have been through it before, and there are a lot of women on here who are happy to talk to you :)