Irregular

[Baby Girl 704]

Umm.. i had period for 3 years and i been noticing its stays there for 8 to 12 days not 7 like normal should i be conserned by it?

[Antares]

I do not think that this is a huge problem. Your body is continuing to change everyday and I think that it is just changing and eventually will change until womanhood. Even if that means the length of your period. I think you are fine.

[Gumleaf]

during puberty periods can be irregular in both how often they occur and the length of time they last for. however, if you are concerned about it, i would suggest that you see your doctor. i would also suggest that you read this this post as well, it may give you some more info.
http://www.virtualteen.org/forums/showthread.php?t=25983