Uy mama, I know this is stressful, kaya please go see your OB-GYN as soon as you can, 8 days late with spotting and a negative PT needs a doctor's check to know what's really going on, okay? Hindi kami pwedeng mag-guess on this one. A few of my mum friends had similar situations, at lagi naman may clear answer once they got checked in person, sometimes it's stress, sometimes it's timing, pero kailangan talaga ng proper exam. Take care of yourself, and don't worry too much until you know more.