Just start saying random names in your head, one might click. A book might help with that, don't get bogged down with meanings, if it sounds right when you say it that is the one.
As a secondary thought maybe think of nicknames that could be made from the name, so you can pick a long one and shorten it, like Cassandra (Cassy).
How about Penny?
Thinking through the alphabet, here's a list of letters I came up with that I'm alright with. I love narrowing things down.

A,,B,C,E,J,L,M,P,S, and T.
I'm shying away from C, like I said before, but I'm hesitant, because almost anything else sounds really different, which isn't a BAD thing, but eh... What we need is a name store, that's like a shoe store, where you can go in and try them on.