Negative Tests

Raquel
Has anyone ever gotten no positive tests before AF was due but still been pregnant? 
With my first, it was a surprise so by the time I took a test, I was 5 days late. With my second, I had a positive test a few days before I was due but I don't remember how many. 
Is it seriously possible to be pregnant but not have hcg levels that are detectable on an ept?