You want to keep the long name, but just call her by a different shortened version than the shortened version you're currently using? I hope I'm not confused, but I think that's what you were saying (but others are assuming you want to legally change it to a completely different name)...? Either way, I think you should do what you want to. It's not too late (how old is she, anyway? I assume from your ticker, she's a newborn!).