Hcg levels

On the first I got blood work done and my hcg levels were at 63, I got more blood work done yesterday and its at 163. Hcg levels are supposed to double every 31-72 hours for early pregnancy. It had been a whole week , shouldn't my levels be higher? I'm trying not to stress, I asked her if everything looked okay and she said for now yes (didn't sound very reassuring). Anyone else have/had low hcg levels and still have a healthy baby? So afraid of having a miscarriage😥😟