Thanks for query,
Your delayed period was due to hormonal
At the age of puberty
& then after our brains Pitutary gland releases precursors that ordered our adrenal gland to produce sex hormones.
The level of this hormones in blood at different period of cycle is responsible for ovulation ,preparation of uterus flow of blood say your menstrual cycle.
Any abnormality in this level causes delay periods.
This may be due to tension.Anxiety
,Shift duty,long working hours,or any ovarian disease
This cause you delayed bleeding .