Hcg level 3700

My midwife just called and told me that on Friday 3-25 my hcg level was 3700. She said my progesterone level was normal. She said she wants me to come in Thursday 3-31 for more blood work to see if my hcg level is rising. She said she was looking for a hcg level of 25,000. I'm worried because I done some calculations and by the time I go back to see her my hcg level won't be that high if it doubles every 48 hours like she said it should.