What’s wrong with me?

I don’t get my period because I breastfeed. My boyfriend and I don’t use any type of birth control.

Friday night I started to get a small amount of dark brown discharge that got lighter and eventually stopped by Sunday afternoon. Last night before bed I had a small amount of a light brown milky discharge. I didn’t have anymore for the rest of the night. I woke up and didn’t have anything at all until this afternoon. I had a big glob of an off-white discharge that had streaks of dark brown blood. It almost resembled my mucus plug like when I was in labor.

Note:I’ve taken several pregnancy tests and other than what I think was a couple hefty indents on FRER, they’ve all been totally negative

My other symptoms: extreme fatigue, constant headaches, very mild cramping, sore nipples, nausea, food aversions