My last normal period was April 26, 2012. On May 26, 2012 I had a very light period that lasted only two days. It was not enough to fill an entire tampon at any time. I usually have a moderate to heavy flow, usually every 30 to maybe 32 days. Since May I have had very tender breasts, nausea, headaches, frequent urination , and somewhat tired feeling. I just took a HPT and it came out negative. According to a Pregnancy Calendar I would be at 5 weeks right now. I do take Metformin and Levothyroxine , can any of these medications be giving me false symptoms of pregnancy or false negative readings on a pregnancy test? Thank You.