In my situation they were low and going up but sometimes they would double and sometimes they would not. At around 4wk 5dy it was 161 and by 6 wks it was still only 1200 or 1300 and u/s could not find anything in the uterus. I probably should have mentioned that part in the other posting also.
All the info on the net says that there is a lot of variability in the HCG range but RE told me that since he knew when I conceived, that my HCG should be at certain levels. He said the variability in the tables is mostly due to variability in time of conception. He said there are always a couple of non-text book cases but typically, if you know when you conceived, you should expect to see certain levels. I did not want to believe him at first but in end, there was no doubt that he was right.
I dont know if this will help. I have a good friend whose daughter in law had the same thing that happened to her as you. She got pregnant ,but everytime she would m/c . This happened about 3 times. Finally she got pregnant and just had a baby girl. She said if she miscarried again she would adopt , but she made it and is now a mother, It did happen for her. Also she was in her mid 30s. I hope this helps you. GOOD LUCK KIM