Period before pubic hair? Options

[rockable]

Ok.. so my sister is 11, and she says she has started her period.
Thing is, she has no pubic hair according to mum, and has only just started getting the whole, breasts getting lumpy and greasy hair (which i thought was the start of puberty right?)
So I dunno what the hell to think, because I was under the impression from all the sex education, lessons from mum, internet etc, that your first period comes after your hormones have finished everything else.. last, and that greasy hair, development of pubic hair, growth spurts, putting on weight, acne, mood swings, discharge, hips changing etc came first?!
Is this normal? Could she be faking and have tricked my whole family? :S

I really want to know because its really made me feel like crap because I am a really late developer, and she has always been better than me in that sense, and when I started my period a few months back I felt so good, because I had finally proved to myself that yes, I am 5 years older than her, and I finally felt grown up. Now I just feel like a kid again because a stupid 11 year old is already over taking me! I dont get it.

[rockable]

I think I have a right to be jealous. That my own sister, who is 5 years younger than me, starts her period at basically the same time? Anyway, its not about me, Im just really curious to know.. because its totally mucked up my understanding of the human body! lol

If its normal, how come she started her period like, straight away without everything else? As I said, isnt your menstrual cycle suppost to come last in puberty? After everything is developed?