Please help!

November 16th, 2014 I woke up feeling as if my bladder was going to explode so I went to the bathroom and grabbed a pregnancy test and it came back PREGNANT!!! I was so excited because we have been TTC for a couple months now. Later that same day I went to the store to get a test to tell me how far along I am and it said "not pregnant"... What is gojng on? I'm not on ANY meds whatsoever, what could this mean?? Am I pregnant or not :'(