Question about plan b

I took a plan b on the 3rd January and had heavish spotting 13-15th. Like it was never anything much really just didn't want my underwear to get dirty. Anyway since then I've been spotting brown on and off sometimes pink. My AF was due 21st but is a no show so far. I have a history of miscarriages so taking a test at this point is too much for me and there's personal reasons why this situation even occurred which I know was stupid to let it happen but stuff. Anyway has this happened to anyone or has my plan b failed. It failed on me before in July last year. Attached a photo of the discharge I'm getting. My pads generally look like that at the end of the day just tiny brown spots.