Hi there, hgreenway is right. Irregular periods when young are common. we can have a late period for a variety of reasons including stress, underweight/overweight/exercising too much, major changes in routine, illness, etc. Also, our hormones can have a blip that affects our period. Our thyroid can be slow (my issue at one time). Etc.
If your period doesn't show in the next couple of weeks, I would contact your doctor and try to be seen. You may need something to regulate you which is often birth control pills (they do more than just prevent pregnancy! )
good luck to you sweetie
ever body type is different some like that to . you will be fine if are still wording about it see a dr.
Could be stress related. Also for girls who are underweight, they tend to have irregular periods or they could vanish all together.