HELP!!!!

Hi guys!i need yall to help me on something or give any important about this,but so ive been missing my period for months now,i am 14 years old and no im not sexually active...im still a virgin i have informed my grandmother about this,but she keeps telling me that is is normal for me to not have my Period for months..Can you guys give me any information about this?!?Thank you and have a wonderful day!!❤️💙💚