hey check this site out it tells you about hcg levels, you are right in between. some peoples dont double, but as long as they are rising its a good thing
http://www.americanpregnancy.org/duringpregnancy/hcglevels.html!
everybodys different. my levels were at 1400 at 3 and a half weeks.
my dr. said not to worry, they look okay...but they seem low and it freaks me out that there not doubling faster
there going up is good. and also sertain factors such as not getting them done at the same time of the day and diffrent clinics can make them off a bit. aslo some people just rise a lil slower than others
did your dr say anything when she told you your levels? i think it can take 48-72 hours for them to double. good luck!