I'm about 5'3 and a size 0, would a small...
I'm about 5'3 and a size 0, would a small be too big?
It all depends on how many layers you wear. The more layers you wear the more room you want. So if you wear more than one or two layers a small might be a good idea. I normally wear a medium size in pants but my medium snow pants are a pain in the neck when it comes to layers. Definately go with more room for layers.
Yes, you will need a XS. I wear a small and my pant size is 3.