It's most likely just an off period. I'm 14, and just got mine this year. Ive missed months and gotten it longer then the 'usual' so you are prob fine. I think it's normal to have it off 'schedule' in the beginning. (Assuming you recently got it?) if you do feel like you still wanna talk to someone about it, ask your mom, doctor, or the least awkward option an older sister if you have one?
It's very normal for a irregular period in the beginning and even later on and unless you have a sex you aren't pregnant - it's probably nothing but if your still worried talk to your mom or older sister