The short answer here is: because they're your boobs, not hers. Ultimately, every one of us is unique before, during and after puberty.
There’s no real way to predict what your boobs will look like or how much they’ll grow. Just like we never entirely know how tall we’ll be or what shoe size we’ll end up with. But there are some indicators about what might happen for you (and when). We look more closely at the ways your body might change over here.
If this does happen, try not to worry. Bigger boobs don’t mean frumpy undies – there are plenty of great bras for fuller busts, and supportive styles that will keep you comfortable whether you’re dancing or doing sport. Typically, you’ll start your period about two years after your boobs start growing.
Well, their rapid growth might be the first sign that puberty is happening. So, that will explain why all your favourite rings no longer fit your fingers, or the shoes you love give you sore toes now.
Their arrival suggests puberty’s in full bloom. For 85% of girls, hardness under the nipples (AKA breast buds) are the first things to make an appearance. While this may feel scary, it’s Mother Nature’s way of helping you transition into the unique person you’ll become.
By the time you get your period, you’ll have had most of your major growth spurts. We say most because although it’s unlikely your height will increase much, your boobs could go on growing for a few more years.