just go out and buy some panty liners and wait for your period. It isn't as fun as everyone made it sound. TRUST ME. It is very annoying and I wish I had enjoyed my time without it. I am 13.
I know how you feel. I was 15 when I started my period, and for all the year from the age of 11, I was just WAITING for my period to come. All my friend would stand there discussing their periods in front of me and I felt...left out. Like I wasn't a woman. I wasn't GROWN-UP, like them. My Mum wasn't worried at all, but I was! What if I never started? Would I need to go to the doctors? I'd just about got my head around the fact that I would be the girl who never started her period, until on one unexpected day...it came. And I regretted EVERYTHING that I had ever said. Trust me, I know that right now you just want to seem 'normal' and 'grown-up' like your friends, but periods are not a joy at all! You're lucky to start late because no matter what age you start, they continue into your adulthood, so it's best that you start as late as possible so that you get less periods!:) Don't worry, I PROMISE you that it will come, I felt like you once. :)
Don't worry i never started mine until i was 14, all girls start developing hair and breasts from the age of 8, i started growing boobs at 8, they didn't grow past B cup though but i'm not bothered because big boobs can be painful, periods can start any where from the age of 8 years to 15 years old, just because your mum started hers at 14 and your grandma at 13 doesn't mean yours will, just be on the look out how that your 14 though because that's the common age most girls start, keep some pads in the house and in your bag for when you DO start because you tend to get your period at different times of the day, i got detention at school once because i was late because it started on my lunch break lol, had to run around looking for a pad to put on. Best pads to buy is ultra towels with the blue liquid stuff in them and wings, they are much comfier and stay put.