Let's seeeee.....You could have Dizzy Izzy, or Grabby Gabby, or Frizzy Izzy, or ..... I like both names! How about giving her BOTH names.....I mean why not have a middle name? Gabriella Isabel? Isabella Gabriel? Then, as her personality develops, you see which "call name" suits her best.
Besides, with a double name you can really get her attention when she's naughty......Remember when you were little and you were naughty and YOUR mother called you by your FULL name?