Hello,
If you have not had intercourse, then this delaying of
periods can be due to conditions that affect the
ovaries, uterus, hypothalamus, or pituitary gland. It could be hypothyroidism, post pill amennorhea , polycystic ovarian syndrome or less frequently a pituitary tumor causing high prolactin levels or a hypothalamic disease. Seek a gynaecologist immediately who will take a careful medical history ,a physical examination and investigations.
I hope it helps.