No BFP because of implantation?

This same day last week I went to the bathroom and had brownish discharge/pink discharge. I've been feeling very sick, dizzy, sore boobs, headaches, loss of appetite (not like me at all), & very very very tired. (Side note: I've been ttc for over a year and have PCOS) So I've been testing for about 5 days all which were either vvvvvvvvvvvf positives/negatives and one indent. Could my negatives be because I'm still having implantation and don't have enough hCG to dectect on a strip test?