those shoes aren't sold in stores - they were a special edition that Simone did for Nike. Trust me, I looked for them cuz my bf is a freak for Nike Dunks! But if you look closely at the pics, you can see that all the designs are painted on. The only company that does Tokidoki sneakers is Fornarina - they're very hard to find tho, some Bloomingdales have them.
**Also, i'm 5'6" and a 36B and I ordered a Medium. Mostly all my shirts that I own are either Small or Medium. (I was surprised to fit in a Small in A&F!) I think you should be ok, depending on how tight or how loose you like your shirts. If worse comes to worse, you can always exchange it.