Advice

Me and my boyfriend are trying to concieve and I got my period on Monday but it only lasted 2 days. My last day of it was Tuesday, yesterday. One day before i started my period I was spotting dark brown stuff. The day i started it was heavy and my cramps were bad but it was dark brown at first and not to much longer it turned very very liquidy and more like a pinkish/ light redish and i was still spotting the dark brown stuff. It didn't look like a period. The color or anything. Ive never done this before so kinda curious of what it could be. And ive never had this short of a period either. I took a pregnancy test and was negative which is unexpected.