Why haven't you hit puberty yet?
Don't worry! It will start soon enough. The daughters of a coworker, both girls are 15 and they still do not have their menstruation.
Boys usually start puberty around 12 to 14-years-old or even later, in some cases not until 16-years-old so you just might not be ready yet.
Similarly girls usually start around 11 to 13-years-old but it can be earlier or later as everyone is different.
You will start when your body is ready, but if you are worried about being late in starting then a visit to your doctor should put your mind at rest. There are hormonal treatments available to bring on puberty but they will only use them if they think it necessary.
See the Related Link below for Delayed Puberty.