Pregnancy after miscarriage

I had two miscarriages this year. I found out I am pregnant again. Yesterday I went to the doctor, he prescribed progesterone, baby aspirin and blood work every two days to test hcg levels. I am 41 years old. My hcg levels yesterday at 13dpo was 235. The nurse said I would be about 5-6 weeks for that level. Clearly I am not as my period was not even due until Thursday. My question is.... Is this a normal number? I have read high numbers can indicate twins? What are your thoughts? I go back for my second blood work tomorrow.