It depends on a number of factors really. There is no 'right' size as everyone will have a different opinion on the 'right' size.
Skinny and slimmer girls are more likely to have smaller chests so AA/A/B cup.
Average girls are more likely to have an average sized chest so B/C cup.
Larger girls are more likely to have large chests so anything from a C/D cup onwards.
I would say the majority of 18 year old girls would have finished puberty a few years ago so their current chest size will be the same/roughly the same their whole life if they don't gain or loose much weight. If they were a late bloomer they may have a cup size to go.
Don't stress about it too much! In the grand scheme of things the size of your chest has little importance.
*everything I've written is purely my own opinions so please don't regard it as 100% truth or be offended by it etc*
It depends on a number of factors really. There is no 'right' size as everyone will have a different opinion on the 'right' size.
Skinny and slimmer girls are more likely to have smaller chests so AA/A/B cup.
Average girls are more likely to have an average sized chest so B/C cup.
Larger girls are more likely to have large chests so anything from a C/D cup onwards.
I would say the majority of 18 year old girls would have finished puberty a few years ago so their current chest size will be the same/roughly the same their whole life if they don't gain or loose much weight. If they were a late bloomer they may have a cup size to go.
Don't stress about it too much! In the grand scheme of things the size of your chest has little importance.
*everything I've written is purely my own opinions so please don't regard it as 100% truth or be offended by it etc*