My blood test came back at an HcG level of 21. The doctor said this is inconclusive. Advice?

I took an hpt this afternoon and it showed a very light line, so I had blood work and they said that anything below 5 is not pregnant, anything above 25 is pregnant. Soooo, I have to wait two days to have blood work again. Anyone have stories of this happeneing to them? What was the outcome?