Light Brown Discharge

[susurrus]

My LMP was on December 23 and lasted 5 days which is relatively normal for me. According to my app, my next period is not expected until February 22. (I have an average cycle length of 61 days- since coming off BCP in July my cycles have been 52, 61 and 71 days- and it appears that I get my period every other month. I have been suspected of PCOS but not confirmed, although I feel its more likely that I only release eggs from my left ovary as that's where I normally cramp when I do.) Anyways, on the 17th I started having light brown discharge (with a slight pink tint at times). It lasted 2 days and was only ever there when I wiped. I took a HPT on the 21st but that was BFN. I have had no spotting since then or anything that resembles a period. I have still been cramping on and off, aside from that I'm occasionally nauseous and just really tired with a backache. Do you think that was too early to test and what I experienced was IB? Or could that have just been my period for the month? I don't want to test again just to see another negative.