[name_m]Hi[/name_m] there.
Here are my thoughts on your list-
[name_u]Georgie[/name_u]-I adore this for a nn. It’s super spunky & sweet. It’s way nick-namey though in my opinion. [name_f]Georgia[/name_f], [name_f]Georgina[/name_f] or [name_f]Georgiana[/name_f] are all gorgeous options. The latter two being more unique, but [name_f]Georgia[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f] sounds gorgeous.
[name_f]Ottilie[/name_f] (Otti or [name_f]Tilly[/name_f] nn)-Super sweet & different. [name_f]Ottilie[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f] is beautiful.
[name_f]Cecily[/name_f] ([name_f]Cece[/name_f])-[name_f]Cecily[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f] is beautiful too! I don’t care for [name_f]Cece[/name_f] though myself. [name_f]Cecily[/name_f] on its own is gorgeous. I don’t think that [name_f]Cece[/name_f] flows super great w/your ln either.
A few other ideas-
[name_f]Amelie[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f]
[name_f]Adelie[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f]
[name_f]Beatrix[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f] nn [name_f]Bea[/name_f], [name_f]Bess[/name_f], [name_f]Bette[/name_f] or [name_f]Trixie[/name_f]
[name_f]Coraline[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f]-Okay, the flow isn’t perfect, but isn’t [name_f]Coraline[/name_f] lovely?
[name_f]Daisy[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f]-I’m in love w/[name_f]Daisy[/name_f]. I don’t want it getting too popular, but I’ll suggest it just in case you love it. 
[name_f]Eloise[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f] nn [name_f]Lulu[/name_f]
[name_f]Frances[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f] nn [name_f]Franny[/name_f] or [name_f]Francie[/name_f]
[name_f]Francesca[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f] nn [name_f]Franny[/name_f] or [name_f]Francie[/name_f]
[name_f]Greta[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f] nn [name_f]Gigi[/name_f] or [name_f]Gerty[/name_f]! I love [name_f]Gerty[/name_f] so much.
[name_f]Hattie[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f]
[name_u]Indigo[/name_u] [name_f]Catherine[/name_f] [name_f]May[/name_f] nn Idgie
[name_u]Juniper[/name_u] [name_f]Catherine[/name_f] [name_f]May[/name_f] nn [name_f]Junie[/name_f] or [name_f]Juno[/name_f]
[name_f]Junia[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f] nn [name_f]Junie[/name_f] or [name_f]Juno[/name_f]
[name_f]Josephine[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f] nn [name_f]Posy[/name_f]
[name_f]Louisa[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f] nn [name_f]Lulu[/name_f], [name_f]Lula[/name_f] or [name_f]Lola[/name_f]
[name_f]Magnolia[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f] nn [name_f]Maggie[/name_f] or [name_f]Mally[/name_f]
[name_f]Olive[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f] nn [name_f]Livy[/name_f]
[name_f]Phoebe[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f]
[name_f]Polly[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f]
[name_u]Ruby[/name_u] [name_f]Catherine[/name_f] [name_f]May[/name_f]
[name_f]Rosalie[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f]
[name_f]Tessa[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f] nn [name_f]Tess[/name_f]
[name_f]Tallula[/name_f] [name_f]Catherine[/name_f] [name_f]May[/name_f] nn [name_u]Tali[/name_u], [name_f]Tula[/name_f], [name_f]Lulu[/name_f] or [name_f]Lula[/name_f]
[name_f]Hope[/name_f] this helps. 