What Causes Delay In Periods?

Hi, I am 23 year old. before marriage my period cycle was 28 days but after marriage first time my periods late one day and 2nd time it was two days late and before periods I have white watery discharge and before 7 days I have pain in my right lower abdomen. and I take home pregnancy test when my periods late for two days and it was negative? is it normal to late periods in every cycle or symtoms of something other?