3 Days Late, 4 Negative Cheapie Tests, Pink Tinged Discharge

How many days should I wait to go get an expensive brand test? I got the ones I used in bulk off amazon, little dip ones. I was reading that pink discharge in lieu of a period may be implantation bleeding. We did have sex on my ovulation day.

I'm just confused as to why I'm late but am getting negatives? But if it's just implanting now, I need to wait a couple more days right?