I have a question about the Kroger pregnancy test. Any help?

My boyfriend and I have been having unprotected sex since we have been together (eight months) and I have never had a pregnancy scare. Stupidly, I figured I could not get pregnant since I was never pregnant within the eight months we have been together. Well, I am thirteen days late for my period, so today, my friend, Deborah, and I went to the City Market and bought a Kroger brand pregnancy test that comes with two tests. Around seven o'clock tonight, I took one of the tests, and the "vertical" like was very dark, but the "horizontal" line was very faint. What does that mean? I am going to take the other pregnancy test first thing in the morning, but I was wondering if this has happened to anyone else and if it means your pregnant. Thank you for your time.