Coming up with a name for unexpected twin girls

My husband and I just found out we are expecting twin girls. We have a toddler son named Ceren. We were thinking about Fiona if it was a girl but now we have to come up with another name. I like Clara but I don't know if it goes with Fiona. I also like Celine but the fact that it's not a five letter name is driving me crazy, as weird as that sounds. Ceren and Fiona are five letter names so I would want the third name to be one as well. I'm super hyper focused on stuff like that and it would bugged me for the rest of my life if I go another route, lol. My husband doesn't get it but it's my stupid quirk, I guess.

My husband also like Amara but I don't. We tried out Irena, Lilia, Giana (too rhyming), and Liane but nothing is holding up. Any suggestions? TIA!