Hcg numbers didn't double

Ja
I'm so sad and I'm trying not to cry but I got my hcg numbers back and they didn't double like they were supposed to. I'm 5weeks 2 days and when I got my numbers checked the first time it was 11257 and now it's only 15578 and I know it's not good.... I suffered an ectopic in January and I was really looking forward to this pregnancy and I'm sad now....