I know this is a little stange but my little sister who is 14 wanted to know why she hasnt gotten her period yet? (just turned 14)

Depends. Puberty normally happens at a wide range of ages. Family history (when did mom, older sisters, aunts start their periods?), nutritional status (underweight girls tend to start later), & more affect when the period starts. As long as other signs of puberty are progressing normally (hair pattern, breast development) this is usually normal. Have her discuss it with her pediatrician if it bothers her.
Puberty. Girls average age for starting menstruation is age 12. But puberty can start as early as. 8 y for a girl, by that i mean breast development. 14 is still normal as long as she has already started showing other signs of puberty, breast development, axillary hair pubic hair.