doctor just called and hcg didn't double

I went to the doctor for my first blood test around 2:30 last Wednesday and then again Friday at 8:30 am. She called me this morning and told me that my levels did not double like they had expected them to.. I am 5 weeks and 1 day today. On Wednesday I my hcg was at 121 and on Friday was 203. Just wondering if anyone else's levels didn't double at first and/or what your levels are at if you know them. I know every pregnancy is different, I'm just trying not to stress out. Thanks!!