Is something wrong beside me?

I'm 15...started puberty a few years ago..and have adjectives female puberty "symptons"(period,pimples,blah blah blah..)but I am flat chested...my sister already have breasts and she's only 11!is here something wrong with me? no worries I am flat chested to and i'm 14 almost 15 so your not the individual one don't worry
No, you're still growing. confer it time they will come.