Ours period underwear are regular in size and correspond to most underwear you already have in your drawer.

Panties in cotton will be experienced as more stretchy in the fabric than panties in mesh. 
If you are between two sizes, we would therefore recommend that you take the smaller size. 

Here are the goals of Everyday flow Brief - low rise (cotton). 
To compare, lay a pair of your own panties flat on a table and measure them hip to hip.