Stressed or Pregnant?

The past two months have been crazy for me. I had my last regular period on december 9th and it lasted through december 12th. My boyfriend and i are in a long distance relationship and i flew out to see him on the 20th of December and stayed with him through the 2nd of January.During this time i was on the pill which i started taking on December 16th. After i spent the holiday with him, i moved to another state and have started college. This past month, my period was 4 days late and when it came it was extremely light. It came on January 8th and lasted ended the 12th, but it was very light, like spotting. Also, i have been experiencing shooting breast pains, frequent urination (2-3 times an hour) and the past 3 or 4 days i have been having a light brown discharge, but not enough to wear a pad or tampon. I thought implantation bleeding, but the numbers dont match up because the last time i had sexual intercourse was on the 1st of January.
Also this could be stress related seeing as i moved away from home and have started college. I have never had a late period before, nor this kind of spotting....any ideas????
THANKS!