I am 5'3" and 150 pounds. Medium fit very comfortably. But a big flaw is that it is kind of see through. I bent over to get something in my BFs car on a sunny day and he was able to see my underwear (underwear was same color as pants). Should be fine as long as you don't post in a way that stretches the fabric or are in a dimmer area.
Image attached is my thigh and you can see my skin tone. The pants I bought we're dark blue.