I took 3 pregnancy tests over the course of 4 days at different times of day. All read negative. I am nauseated at night and a little during the day. I have cramps sometimes just on one side. I am peeing a little more than usual and have a little discharge. Is it possible that I am pregnant? I went to the OBGYN on the 14th (3 days before my period was due) wouldn't the Dr. Have noticed or is it possible that I very recently got pregnant?

The doctor would not notice unless you asked for a pregnancy test. Also please read and follow the home pregnancy instructions, most want this to be with the very first urine in the morning. ( not different times during the day)

But yes this is one possible reason, but there are others, try retaking the test early in the morning, if not, revisit the doctor for a professional testing