Cycle Day 28 more implantation bleeding??

Today is cycle day 28 (avg cycle is 32 days)

So today is the third day I have noticed pale very light pink-brownish discharge. It’s been coming and going does not fill a pad or liner. Today there was a bit more than last two days, please see photos below.

Period is expected on 18/2 according to GLOW. Normally don’t get spotting this early and it doesn’t feel like a period. Mostly appears when wiping.

Positive OPK 3/2

BFN this morning

Thoughts? IB or AF?