Sizes at popular stores?

I have only been shopping at Aeropostale and AE so far, but I'd like to start shopping at some of the other stores. I can only wear shirts from both of them, as bottoms are too big for me, even the 00 (I still have to shop in the kids' department for my jeans and stuff. :( ). Anyway, I wear an XS in both of them, because the smalls are too baggy on me. Would I still wear an XS in Hollister, A&F, Wet Seal, etc.?