I am buying a pair of Cressi Gara 3000 LD bi-fins and I am not sure what size to buy. I normally wear a US size 11 or 12 but they are split up 10-11, and 12-13. I don't wear diving socks but I might if they are a little big. I am wondering if they run large or small so I know which one to choose. Any advice from experience with these? Thanks