Congratulations! I actually think [name_m]Riven[/name_m] is really pretty and unique, though I do see it as a bit more masculine.
Some more ideas you may not have considered:
[name_f]Avalon[/name_f] / [name_f]Azura[/name_f] / [name_f]Astoria[/name_f] / [name_f]Aspen[/name_f] / [name_f]Arwen[/name_f] / [name_m]Arian[/name_m]
[name_m]Caleo[/name_m] / [name_f]Claudia[/name_f] / Cerrus / [name_f]Cerise[/name_f] / [name_f]Capri[/name_f] / [name_f]Clarisse[/name_f]
[name_f]Darcy[/name_f] / [name_f]Dawn[/name_f] / [name_m]Devin[/name_m] / [name_f]Delphine[/name_f]
[name_f]Elowen[/name_f] / [name_f]Elara[/name_f] / [name_f]Ellian[/name_f] / [name_f]Elodia[/name_f] / [name_m]Evren[/name_m] / [name_f]Ember[/name_f] / [name_f]Emery[/name_f]
[name_f]Freya[/name_f] / [name_f]Fallon[/name_f] / [name_f]Farrah[/name_f]
[name_f]Haven[/name_f] / [name_m]Hartley[/name_m] / [name_f]Hyacinth[/name_f] / [name_f]Hadley[/name_f]
[name_m]Jules[/name_m] / [name_f]Jovie[/name_f] / [name_f]Josephine[/name_f] / [name_f]Jubilee[/name_f]
Keitah / [name_f]Kaia[/name_f] / [name_m]Kaida[/name_m]
[name_f]Linnea[/name_f] / [name_f]Lenora[/name_f] / [name_m]Lowen[/name_m] / [name_f]Lydian[/name_f] / [name_f]Linette[/name_f] / [name_f]Luetta[/name_f]
[name_f]Maren[/name_f] / [name_m]Madden[/name_m] / [name_f]Merritt[/name_f] / [name_f]Mavis[/name_f] / [name_f]Marceline[/name_f] / [name_f]Maeve[/name_f]
[name_f]Nadine[/name_f] / [name_f]Nerissa[/name_f] / [name_f]Nikkita[/name_f] / [name_f]Natasha[/name_f]
[name_f]Ophelia[/name_f] / [name_f]Odelia[/name_f] / [name_f]Odette[/name_f] / [name_f]Oriana[/name_f] / [name_f]Ottilie[/name_f]
[name_f]Paige[/name_f] / [name_f]Pandora[/name_f] / [name_f]Phoenix[/name_f] / [name_m]Penrose[/name_m] / [name_f]Phryne[/name_f] / [name_m]Peyton[/name_m]
[name_m]Rowan[/name_m] / [name_f]Ramona[/name_f] / [name_f]Reese[/name_f] / [name_m]Robin[/name_m] / [name_f]Raven[/name_f]
[name_f]Seren[/name_f] / [name_f]Sabine[/name_f] / [name_f]Saela[/name_f] / [name_f]Selena[/name_f] / [name_f]Sereia[/name_f] / [name_f]Seraphina[/name_f] / [name_f]Sabre[/name_f]
[name_f]Twila[/name_f] / [name_f]Tabitha[/name_f] / [name_f]Tarren[/name_f] / [name_f]Teagan[/name_f]
[name_f]Yvaine[/name_f] / [name_f]Zinnia[/name_f]
[name_f]Hope[/name_f] this helps!