Really sorry to hear about your Willow 
I like Wynter (the sound anyway - would probably spell it conventionally, personally) but not sure it goes with Charlie - they're two extremes in the normalcy stakes really, aren't they.
If you want something unusual then how about a mainstream name that's just not particularly 'in fashion' right now?:
Amy, Alison, Annette, Ailsa, Bryony, Belinda, Bethan, Claire, Christina, Danielle, Emma, Eilidh, Esther, Fiona, Frances, Hannah, Harmony, Iona, Joanna, Jennifer, Juliet, Jocelyn, Jacqueline, Jodie, Kimberly, Kirsty, Kirsten, Laura, Leah, Megan, Miriam, Melanie, Melissa, Nicole, Nicola, Natasha, Paige, Ruth, Rebecca, Rachel, Rhiannon, Susannah, Sorrel, Tamsin, Tiffany, Victoria, Vanessa, Zoe