For the record, I think the right type of girl could totally rock a name like
Myrtle. It sounds like a quirky, unapologetically brash kid who marches to the beat of her own drummer. :)
Since you seem to like old-fashioned names, I'll suggest some more of those:
Myrtle AmeliaMyrtle BeatriceMyrtle ClariceMyrtle Dee Myrtle EdithMyrtle FayMyrtle GreerMyrtle HollisMyrtle IreneMyrtle JosephineMyrtle KayMyrtle LornaMyrtle MaureenMyrtle Nora/Norah
Myrtle OliveMyrtle PatriciaMyrtle RuthMyrtle SuzanneMyrtle ThereseMyrtle UrsulaMyrtle Vivian/Vivienne
Myrtle VirginiaMyrtle WinifredMyrtle WilhelminaMyrtle Yvonne