I named my DD Abigail, even though I too was a little worried that it was becoming too common. It's good to know that it's not really as over-used as it would seem. I think Abigail Isabella is very beautiful. I call my DD Abby Rose, so I agree with the pp that Abby Belle would sound very cute.
Thank you for your kind words. My wife and I adore Abby Belle. I'd like to ask you question though. How old is you daughter now, and if she is in school, are there any other Abigails in her class, school or just generally around on the playground? Thanks again, this helps a lot.