Lily - pretty. Was so popular at one point that it started to seem a bit nothing-y but I think that might have passed. I quite like it.
Ruby - quite like it.
Laurel - not keen. But it would be unusual on a child at the moment.
Isla - like it. Not quite as everywhere as Lily was a few years ago but obviously there's a lot. Not as issue if that doesn't bother you though. Popular names are popular for a reason.
Rose - like it. Simple and elegant. Allows for Rosie as a cute nn for a little one if you want.
Amber - like it. Don't meet too many.
Alba - really like it. Never come across one but I think it's really pretty and a bit different.
Romy - really like it. Probably as a shortening of Romilly but it could stand alone.
Erin - really like it.
Sadie - love it. I'm always surprised it's not more popular.
April - really like it.
Maeve - not keen but nothing at all wrong with it and definitely not overused.
Maisie - quite like it. It's sweet. Not overly sure about an adult Maisie but, at the same time, I don't think it's short for anything so there will be lots.
Mabel - not keen but don't know why. It's quite sweet.
Sienna - quite pretty. Apparently very popular but I've never met one.
Lottie - not keen but I love Charlotte.
On similar lines (1-2 syllable, sweet, pretty):
Amy, Alice, Ava, Annie, Anna, Asia, Bella, Bonnie, Bronte, Chloe, Cassie, Callie, Calla, Carys, Daisy, Darcey, Delphi, Dana, Eden, Effie, Etta, Eva, Evie, Ella, Ellie, Esme, Edie, Freya, Faith, Fleur, Grace, Heidi, Holly, Hazel, Hallie, Ivy, Iris, Indie, Josie, Jessie, Kitty, Katie, Kiki, Lucy, Layla, Lola, Luna, Leah, Lois, Lyla, Lena, Lyra, Mila, Molly, Millie, Mala, Mika, Maddie, Marnie, Mia, Maia, Nova, Nyla, Nina, Nyah, Nia, Nancy, Opal, Phoebe, Poppy, Polly, Posy, Penny, Pippa, Rosie, Remy, Robyn, Rowan, Sophie, Sylvie, Summer, Skye, Tilly, Tessa, Tansy, Taryn, Una, Veda, Willow, Xanthe, Zoe, Zara, Zia