I like [name]Christa[/name]
I personally wouldn’t choose [name]Christa[/name]… but I think that [name]Christian[/name] is a great boys name and I think that [name]Christianna[/name] or Christiania are really nice choices (with several nicknames) that are similar to [name]Christian[/name] and still feminine. Best of luck! 
Another possibility would be to use the name [name]Christina[/name] (like [name]Christian[/name] but the last a and n are switched around). I also like [name]Christina[/name] spelt [name]Cristina[/name]. Best wishes to you.
I like [name]Christa[/name]. I also like [name]Christiane[/name] (like the journalist Amanpour) and [name]Christiana[/name]. Or you can just use [name]Christian[/name] – there’s no reason it can’t be translated for a girl!
The only one I really like is [name]Christine[/name]. I think its graceful and underused.
i like [name]Christiana[/name]
[name]Christanna[/name]