HCG levels in early pregnancy

Hi everyone. My doctor is off today and don't know who to ask. I have PCOS and never had a regular menstrual cycle (that's why I am not sure when I ovulated) . I was on Metformin and Provera and finally got a positive test. I performed the HCG blood test (quantitative) on the 2/8 and the results were 201 mIU/ml , which confirmed that I am pregnant. Let's assume I was 4 weeks pregnant, because of my irregular cycles. I've done another blood test yesterday 2/13, 5 days apart and the levels are 319 mIU/ml ( assuming 5 weeks now ) . As I know it should've increase a lot more. I am a lit bit worry since I can not talk to my doctor today.