So confused?!?!

So i stopped taking my birth control pill 3 months ago. Not really trying just not not trying. Hubby has been pulling out. Well my period is 6 days late and I keep getting negative tests. I have in the past tried to skip a period and jumped straight in the next pill packet and still got my period ontime so this is abnormal. I don't feel any more stressed than I always am. What gives?