Once your hcg level is above 12000, it can take 72-96hrs for hcg to double so you're close if it takes you 96hrs. Also, was your blood done at the same lab both times? Lastly, the baby's heart rate sounds fine I believe 120-180 is normal. Good luck.
The heartbeat sounds fine. At 14 weeks my son was 130 bpm. At 18 weeks he went up to 147 bpm. At your early stage I think anything over 100 bpm is fine.
My labs where done at the same hospital. But I was so worried that last night at about 1030pm, I went to another hospital and had my HCG levels and the babies heart rate checked again and it was least then 24 hours and my HCG levels had increased to 38870, which is 1370 higher and the babies heart rate is now 141000. The doctor at that hospital said that even if they don't double, that as long as the levels are increasing and in the brackets that they should be in at my stage which is 15000-20000, the baby is fine. So, I don't know. I have an appointment wih my gyne on the 15th and I'm going to ask him since he is an expert in this area and see what he says. Thanks guys for your comments. They are very encouraging.