Hcg at 4 weeks seems low

I just had my first blood test. I had my test the day my period was due. But this is telling me I'm 4 weeks 3 days. Hcg is 168.3

I feel like it seems a little low and now I'm worried. I've had 2 early losses and now after 2 years I'm finally pregnant. I'll have a repeat test Wednesday but until then I'm just a nervous wreck. I've had food aversions, extremely sensitive to smells, slight nausea, cravings, lower abdominal cramping, and pretty bad lower back pain. I know doubling is what's important but I got my positive test 11 dpo so I feel like it would have been higher. Any advice or thoughts is appreciated.