Well actually I've already decided! I am back, as requested, to update this thread
I went to the registry office today to offically change 5 month old DD's name from Eve to Anna, although we have already been calling her Anna for a few weeks. Family and friends have all adjusted well. Only the registrar was a bit 
I am so so happy I changed, feel much better, hadn't realised quite how much I was bothered by the whole thing! We have added Anna at the front of her name so she now has 2 middle names. Even though all 3 names begin with vowels and it is a bit of a mouthful we feel like it is just part of the story of her name now. Thanks for all the comments and advice on my last thread 