First time TTC! Help???

Okay ladies hubby and I are trying to conceive baby #2 my first was a surprise so I didn’t keep track of anything. This time I’ve been taking opk tests but I just dont understand. Glow says my fertile window starts today but I’ve been testing since the 6th I’ve had a vvfl on my opk on the 6th the 7th in the am much darker but not as dark as it should be then yesterday was still faint obviously there still negative so I’m confused. I took this one today guess still negative but I’ve been spotting pink/rusty looking discharge since yesterday morning. It only shows when I wipe. I figured it was ovulation bleeding but my tests say negative. I think it’s to early for implantation bleeding bc I’m on CD 15 and it isn’t my period so idk what’s going on 🤷🏼‍♀️ any suggestions??