I thought I was pregnant?

About 3 weeks ago I started feeling nauseated everyday all day and it worsened in the mornings and at night, also when I would try and get out of the house. I had my period around the 15th of may but I still thought I was pregnant till now because I have all of the symptoms. I just started my period and I'm at a loss of what could be wrong. I'm planning on seeing a doctor Wednesday but I would just like to see what other people think as well. I'm having minor cramps and im not bleeding as much as I usually do.