Could I possibly pregnant?

About a month ago my doctor put me on progesterone. I have PCOS and hadn't had a period since November 2014. When I was on the progesterone I did get a very light period. My fiancé and I had sex unprotected a couple of times. I took a couple tests from the dollar store and they were negative. I have never really worried about pregnancy because my PCOS is severe and I don't ovulate. I only get a period when I am on birth control. Recently I have been feeling very fatigued and nauseous. But I take medication that causes nausea so it could be from that. Today I had a violent vomiting episode and have never felt so terrible. I doubt I am pregnant and can't afford a better test until Friday so I would just like to see what some of you think. I appreciate any input or opinions. Thank you for taking the time to read.