Am I pregnant or is my aunt coming or what?

Okay so this may become tmi and im sorry in advance if it is. My last menstral cycle was december 10th through the 15th. My next cycle is due on january 7th, but since december 25th I have been spotting. Its either been a light pink or a dark brown. So I have been spotting for 13 days now worrying me. I had an ovarian cyst surgery back in july at the age of 22 due to the fact it was huge. It ended up having more then 20 oz of fluid in it. But my cycle has been normal even after that. But this spotting for the last 13 days worries me. Im on birth control but their are days I sometimes forget it, once maybe twice a month but I always take it as soon as I remember the next day. If anyone could help that would be great. This and being tired all the time is annoying me. Ive been up since 330am was scheduled 3 houds to work today and by 1pm I aas ready to hit the hay again. If anyone can help id be greatly appreciative. ThNk you.

i would take a pregnancy test to be sure. there's always a possibility. it also could just be if you only recently first had sex since the surgery that the sex somehow caused the scar tissue from surgery to open and bleed but idk, i'm no doctor haha