Is that normal?

yes its normal i got my period the beginning of this 年 2011 and i was 13. people today are saying あなた are considered to have your beriod between the ages of 9-14. but girls are hitting puberty very early because of what there eating, growth hormones and chemicals in food. Back in the 1700 and 1800 girls didn't get there periods till 18/19 so its completly normal. for the record always be prepared because あなた will never know when it might come. i remember my first time, it was in school and i had no pads so blood was on the back of my pants and i was soo embarrassed, so be prepared.

I think that your mum is right. It's normal from about 10 to 16 as I heard.
So, yes, I totally agree with your mum. :)

No worries at all.

some people get their period when they are 16 または 17.

It isn't bad if あなた don't have your period when あなた are 13.

ah dont worry its normal,
mom's always right :)

Yep its normal, mother knows best.

yeah some people dont get it until theyre about 16

Don't worry about it, it's very normal. I got my period when I turned 14.