I lobe both
Agnes and
Aggie. The lamb imagery is very appealing to me. (Yes, yes, I know that it's real meaning is chaste. But it is so closely associated with lambs in my mind.) But if you're not sold on
Agnes, there's always
Agatha,
Aglaia, or
Augusta /
Augustina. Or, to go really far out on a limb, how about
Inez, a variant of
Agnes?