Clothing - Leggings - Which size?

Hi guys,

my Birthday is coming up and I want to get FB leggings, yeah! As I'm living in Germany and shipping time and costs make it inconvenient to ship items back, I need to make sure to order the right size right away.

My problem is that my measurements are not straightforward and I'm in the middle of sizes :(

Waist: 75cm

Hips: 92cm

So... my waist would mean size M, but my hips tell me to get a size S. Can anyone that had the same problem tell me which size would be a better fit? If it helps, I'm 167cm tall and weigh about 57kg.

Thank you so much in advance!

Edited