Missed first day of period.

Huma

Hello girls, help me out I'm confused. I m TTC didn't get my period on the expected day and on another of the expected period getting little light brown n white discharge after every gap of 9 hours. Today is the third day still the pad is clean , I did the pregnancy test out of curiosity but it is BFN .I'm always regular on periods always gets on time and flow is always normal. I don't understand what is happening please pour some suggestions.

Thank you