Low beta number indicative of anything?

When I first found out my Hcg number was only 81. Now I know that I was about 4 weeks at that time. I had my blood drawn 10 days after and it went to 3,881. You'r numbers should double every day. I would say you are about 2-3 weeks right now just by how low your numbers are, but it is positive. Anything over 5 is positive. Good luck and don't worry. You will be surprised at how your numbers will increase from now until the 31st. Good luck.