Implantation bleeding?!?

Glow said my fertile window was the 19-25 of last month, I don't know my exact day of ovulation though. I have had unprotected sex numerous times a week where we use the withdrawl method... On the 30th I noticed some light pink discharge when I wiped and that lasted until the 31st and went away, then I started getting very light brown discharge which is still continuing currently. It's very light, only when I wipe too. 
​I read that pink discharge a week before your period can be considered IB but what about the brown d/c that is following it? 
​I've taken two test but I'm assuming it's too early to really show, they were both negative. My next cycle is due next week on the 8th...
​Any opinions on the brown d/c following the pink, could that still be IB just flushing out?