Low progesterone

At 7dpo my progesterone was 5.7 I was put on suppositories and today I am 20 dpo (tomorrow I will be 5 weeks) and my progesterone is 10.0. Is this too low? Should it be higher than 10? I’ve been on suppositories for 11 days now and it only went up a little bit. I am worried, but my hcg is doubling perfectly.