If you like Giovanna, maybe Gia would do. It is a lovely name.
Something one-syllable would sound good with those three-syllable boy's names. Jake, James, Mark, things like that. If you want something fancier or more exotic, some of the websites like Nameberry will list up-and-coming names; that works well for middle names.
My name Is leeanna, & my daughters name is asha (Asia) & my sons name is Julian which is unisex. You could try Jillian, Olivia, Madison, codi, Lillian, Geneva.
We are still stuck in the middle of gulianna or korynn for our baby due in November.