M.S.
When my period was 3wks late with my son, and HPT's were negative, they did a blood test, which was positive and the low numbers just meant that I'd ovulated/got pregnant much later than I thought. What's important is that the numbers grow, which show the baby is growing. In addition, lower numbers have nothing to do with singleton/multiples (facts show that higher numbers, as well as faster doubling rates, have been linked to singletons more often than multiples). This can be a fun site to track: http://betabase.info/index.php. Good luck and grow baby grow!