I only know the name because of a sketch in [name_m]Little[/name_m] [name_m]Britain[/name_m] otherwise I would probably say [name_f]My[/name_f]-fan-wee. Otherwise I say the majority of non-welsh people will almost always pronounce it wrong when they just look at it.
[name_f]Mya[/name_f] could be a possible nickname, otherwise I’m pretty stumped, it does mean ‘my lovely little one’ so she could go by [name_f]Lil[/name_f].