Can anyone help me understand?

chemid14

I got a negative two weeks ago. Over the last few days I've gotten four positives. Went to doc and they got a very faint positive. My last regular period was from June 7-11. I had a two day bleed (same heaviness of a period but 3 days shorter) on July 13. The doc thought I would be about 7 weeks because of my info and sent me to sono. They found nothing. Is it possible that my two day bleed was a period and I am just barely along and that's why nothing is there, especially because I showed a few negatives two weeks ago. Doc drew blood Monday and I went back today. Nurse told me that my Monday number was 49. Any advice is welcome. Thank you. We've been trying for a year do I don't want to be overly optimistic.