Congrats to your friend! We like that kind of news around here!
What day were the embryos? Typically, if it was a day 3 transfer and she's 12 days post, you look at the 15 DPO numbers, and if it was a day 5 embryo transfer, look at the 17 DPO numbers.
The other thing to keep in mind is that a low HCG isn't necessarily doom and gloom, it's more important that the numbers are doubling appropriately. Finally, there's a lot of variation in what is "normal" because the numbers grow exponentially.