Thank you for your inquiry.
About TOPSUNNY, the size is decided by top bust size.
The size S-M fits top bust 72-87cm and L-LL fits top bust 86-101cm, so I think you can wear both sizes, but unfortunately, the size L-LL is out of stock now and it will not be supplied in future, so we would like you to try the size S-M.
Please note that it is only guide and the size depends on your figure, the material and the design of the item.
We hope this information helps you.
Thank you so much.