12 dpo with low hcg blood level- is this a chemical?

Looking for those who have had similar experiences. I miscarried naturally back in August and now TTC. I ovulated 10/21, just got a faint positive yesterday 11/2, so that is 11 dpo. Truthfully thought I was going to get AF because I was very crampy and had very very very light spotting the few days prior. My boobs are intermittently sore which doesn’t happen with AF.

Yesterday ( 11/2) I got a faint positive in the AM, then got a blood HCG level drawn, it was 9. Today I go for an ultrasound to see if I retained anything from my previous MC. Still crampy today no spotting or bleeding at all.

I’m worried this is a chemical with my level being so low. Would love to hear from anyone. Had a bit of line progression but I feel like it is faint compared to my pregnancy with my son.