Shorts are very stretchy and come in two overlapping sizes.

Small/Regular stretch from size 00(24) to 16(33) and Regular/Large stretch from size 8(29) to 22(36). If you are size 10 and up go for Regular/Large.

Don’t worry if you are not sure, there is a big overlap between sizes.
And if both sizes fit you, go for the larger one, it will be easier to measure.