Yes, it's completely normal not to have your period at the age
of 14 years old. The average age of menarche (first period) is 13
years old but anything up to 16 years old is considered within
normal range.
you have to chart your period it is about 14 days before your
next period if you have a normal cycle if you dont have a normal
cycle you could use an ovulation kit to see when you are
fertile.