Extreme faint line ???

Arh

My last period was July 20th, 2018. I have taken a ton of pregnancy test, one blood test and ultrasound 2 weeks ago, all came back negative. My doctor wants me to come back in 2 weeks to repeat the pregnancy test. The last 3 days I have had light pink discharge when I wipe and just sometimes and I know it’s not my period . I would say like once a day . I’m so confused 😐 my boyfriend doesn’t see anything .