Need help with HCG levels asap

Thea

Girls - I had a blood test on Wednesday at exactly 6 weeks and my hcg was 11035..

Had my 2nd blood test 2 days after at 6+2 and the hcg level was 18135..

Is this okay?

I alway thought everyday it should double?

Please help me, I had a miscarriage in January & so worried this isn't right?