I am glad you have decided (I was about to PM and ask if you had). I think it is a wonderful name, but I have a question (not only for you, but to ALL people) Why do you plan to shorten the name?? If you like Calli, NAME her Calli. If you like Callista, CALL her Callista. (I by no means want to bring this thread down, but this is a habit that has always confused me)
I asked my mum the same question and she said its because she wanted the full names but realistically people do shorten them. Like my name is Holly and people shorten it to hols and I cannot stand it personally but even a short name gets shortened by lazy people!