Short & Light Period, BFN 🙃

I've searched the Internet for answers, all of them with conflicting answers and none of them all that comforting. I'm just looking for some insight and direction.

TMI WARNING:

Yesterday in the early morning I began brown spotting, very slight. My periods are irregular but according to LH testing I was approximately 14dpo then (15dpo now). I assumed my period was about to begin. My periods have always been very heavy and last between 4 and 6 days. I put a tampon in and went back to bed, disappointed that I wouldn't be getting my BFP.

When I woke up again hours later, i went to change the tampon and it was barely used - more brown with a small amount of red. I took a hpt thinking this was odd and it was a BFN. Six hours later, I changed it again, still barely used but a bit more red so i figured AF was simply sneaking up on me. Fast forward to today, my "period" has pretty much stopped completely. All that's left is a small amount of brown discharge. hpt still says negative.

The only other symptom I have is sore breasts, but other than that I don't have any of my usual cramping (or acne for that matter!)

I'm wondering what you all think. Anovulation? IB? Breakthrough? When do you think I should test again? Has this happened to you?