Hugs hun.. My HCGs this pgcy were:
HCG @ 4W2D = 80
HCG @ 4W4D = 216 (Doubled every 1.4D)
HCG @ 5W2D = 2351 (Doubled every 1.4D)
HCG @ 5W4D = 4948 (Doubled every 1.9D)
HCG @ 6W1D = 15671 (Doubled every 2.4D)
HCG @ 7W0D = 43746 (Doubled every 4.1D)
HCG @ 7W2D = 49325 (Doubled every 11.5D)
I know that my HCG levels were about the middle of the range. Yours are doubling every 3.3 days, which is not that slow.
Check out
this site, which says at 6 weeks your HCG should be between 1080 and 56500.. And your with in that range.
This site has a calculator and says that HCG levels between 1200 and 6000 should double between 72 and 96 hours... and your well within that range too..
So I would say dont worry

Or ask for a US and see if you can see the HB (They saw mine at 5w6d their dates.. (Or 6w4d my dates))
GL hun!