It's possible when you were spotting etc, this is when implantation has occurred. So your numbers would still be low at that point. Which would put you at about 2 1/2-3 weeks.
It is a bit to early to say what is happening. It is possible that this may indicate an ectopic pregnancy or yes, possible threatened miscarriage. But do keep in mind there are lots of woman that do have low levels and delivery a healthy baby. So try to relax as stress won't help the situation at all. It is a good thing that there is no cramping and/or pain at this point.
Best of luck Hun, Hope this helps, If you need anything else please feel free to ask. If you found this helpful don’t forget to click the *accept* button!