Ah sis, yan talaga ang nakakaabala, PT negative pero delayed pa rin! Since you had a CS 2 years ago, pwedeng stress, hormonal changes, or even thyroid issues ang culprit, pero honestly best if you get checked with your OB para sure na, kasi irregular periods after CS can happen pero gusto nating malaman kung ano talaga ang dahilan. Try doing another PT din if kailangan, or blood test lang para mas accurate. Hang in there, marami sa atin ang nagdaanan ng ganito!