I think it's fine to change names...when people adopt adult dogs from the pound, they rename them all the time since many times their names are unknown. They all adjust and do fine with it!
I am obviously partial to Emma, since I have an Emma, but I also
really like Lilly or Lily. I wanted to name Emma that actually, but my husband didn't like it. Lily of the Valley is my "birth flower" (May). Daisies are my favorite flower, and I also thought of that for a yorkie name, but again, DH vetoed, because it was too frilly for him