hcg level 9?

I went to the er today and they said my hcg is 9 so I'm not pregnant? Wouldn't it be zero if I wasn't pregnant? I'm thinking I had a chemical pregnancy because I had positive tests all week then started spotting today and they did a ultrasound and said it's ethier to early to tell or I had a miscarriage. But again my question is if my hcg is 9 doesn't that mean i am pregnant are I was pregnant?