21YO female. I have had light 3 day periods for about 6 months now. I use to have a 5 day regular flow period. This month my period was on December 4th, it ended on the 7th. I had cramps and breast tenderness starting on the 26th of November and the cramps and tenderness have not gone away like they normally do. I have also spotted for 2 days in a row. Even though I am not trying to get pregnant, I took pregnancy tests on the 11th and 16th... both negative.