Kallin or Kylan?

I really love the name [name]Kallin[/name]. I think it is very unique, but not too out-there. I have seen it spelled [name]Kallan[/name], but I prefer [name]Kallin[/name]. However, I do not like [name]Kallie[/name] for a nickname; [name]Kal[/name] is more down my ally. If I go with [name]Kylan[/name], I will definitely be calling her [name]Ky[/name]. The middle name is set as [name]Carter[/name]. Are both names too boy-ish? Are the spellings alright? What are your first impressions of the names? Which one do you think I should choose? Thank you for any input!