When you shop for clothes online there is unfortunately the drawback that you can not just stand and try the clothes. Therefore, we recommend you always look up sizing guides carefully before choosing a size:)
The different manufacturers each have their own targets they produce the garment after, so even if you are a medium in one or more brands, you can easily be small, large or XL in another brand.
If you are in doubt about a product or how you suggest a sizing guide on our shop, you are more than welcome to write and ask until it. Then we would very much like to help and advise on the sizes of the product you have looked at:)