3 months PP, late

I’m 3 months PP and not breast feeding (never started) after having my son I quit bleeding around 2 weeks PP and my period returned 4.5 weeks PP. Since then I’ve had two periods right on time with everything back to normal. Except this month I’m 2 days late with no AF in sight. None of my regular symptoms (cramps especially) BUT I took a test today and it was negative. What’s going on? My last positive pregnancy test showed two lines like 8 DPO. Is it possible I couple be pregnant again and it’s just not showing up yet 😬