I'm 13 also it's normal I've gone 6moths without getting my period b4 I asked my doctor and he says it's normal if it gose on for a month or 2 you should ask your doctor
If you are sexually active, you need to take a home pregnancy test to find out if you are pregnant or not. Otherwise, this is not something to worry about. It's completely normal to have irregular periods as a teen as your body tries to get used to the hormone fluctuations that you have throughout your cycle. Also, stress, illness, medication side effects, weight changes, diet changes, and so on can also cause you to have a late period. It really should not be an issue though and your period will come sooner or later.