I love
Rosemary, and
Romy is a great nn (though I prefer it as a nn and not a formal name) but I would personally use
Rose or
Rosie. :)
Rosemary Pearl and
Rosemary Eve, which have already been mentioned, are great combos but may be a little too word-namey for my tastes. I also like
Rosemary Camille.
My only hesitation in using
Rosemary would be the association with "
Rosemary's Baby". :-/