I am a 23 year old who had been on Metformin 500 mg for PCOS, my doctor put me on it to help me ovulate to increase my chances of becoming pregnant. ever since I have been on this I have had a regular cycle, every 34 days. I am now going a little over two weeks later on my cycle. I have been feeling nauseous, my breast have been felling very tender and sore, and I have felt more tired than usual. I took a HPT and it was negative. Is there a chance that I could still be pregnant? If not what could cause this?