Chemical pregnancy?

Fran • Mom of 2 | PCOS

My period was 5 days late, I tested and it came back negative. Then I got what I thought was a period for 4 days, then started feeling nauseous and having spotting, pregnancy test came back positive. Hcg levels rose to 28 a week after testing positive but my progesterone stayed low. They retested 4 days later and hcg dropped to 19. Now I’m spotting again. Could this have been a chemical pregnancy?