My HCG level didnt double it went from 500-700 in 2 days.. am I going to miscarry?

I found out I was pregnant 4-5 days ago. I am 4-5 weeks pregnant. I had cramping and brown spotting but only when I used the washroom. I got my blood test taken 2 days ago and my hcg level was at 500.. I went in today and it was at 700. The bleeding has stopped and my level didnt double.. the doctor told me he was 90% sure it is going to be a miscarraige. I go for more blood work next Sunday.. but Im wondering if there is any hope? A whole week is going to kill me and it hurts just to type this :(