Am I Pregnant?

So lately I have been feeling moody, sore breasts and a little nauseous in the morning. This morning I decided to take the test even though I’m not suppose to get my period next week (starting Monday) I got a positive test and said 1-2 weeks. I rushed to the closed drug store and grabbed some more and my second test read negative (this one taken around noon). Is there a chance that I am pregnant or is this just a fluke?