Don’t know what to think 😬

I was 15 days late but still getting negative pregnancy test. So I called the ob and scheduled an appointment. She said, “based on your longer period cycles, I don’t think that you’re pregnant but I’ll schedule a blood test just to double check” my levels came back at like 33.5 and the nurse told me that based on that that I was only about 2 weeks pregnant. And that the ob wanted me to come in for an ultrasound in 8 weeks... that’s November 28.... and the nurse told me that if I have any cramping or bleeding to just call them a let them know.... I don’t know if the ob still doesn’t believe I’m pregnant or she thinks I’m gonna have a miscarriage or what.... this is our second. Our son is currently 10 months.