Ii am now 15 days late and ii haven't been stressing and ii'm cramping what's wrong.. ?

Pregnancy test: The first thing to do when you are late is a pregnancy test; if it's positive, the cramps may be a sign of an early miscarriage, or of something worse. You need to check.

Unsure.: Take a home pregnancy test. Reasons for missed / late period include: an anovulatory cycle in which no egg is released, marked v or ^ in weight; eating disorder; Over-exercising (endurance athletics), stress, travel, significant illnesses, oral contraceptives & other meds, Illegal drug use, breast feeding, hormone imbalances and medical problems (i.e., PCOS). Pregnancy is #1 reason.