Uy, ang sakit ng ulo at antok mo pairing, minsan talaga yan nangyayari even kung negative ang PT dahil baka timing lang ng test or hormonal changes pa lang, pero honestly, I'd suggest getting a blood test (HCG) sa OB mo to be sure, kasi mas accurate yan kaysa PT lalo na kung delayed talaga, at para ma-rule out din other reasons ng delay like stress or hormonal imbalance. A few of us moms experienced delayed periods din after pregnancy and CS, at parang minsan ang body namin ay nag-adjust pa lang talaga, pero better peace of mind kung mag-consult ka na with your doc para alam mo agad ano nangyayari! Keep us posted ah, sending you love!