Looking for short (5 letters or less) unisex names.
Currently on my list:
Kit
[name_u]Kai[/name_u]
[name_u]Rowan[/name_u]
[name_u]Sage[/name_u]
*[name_m]How[/name_m] do you feel on [name_u]Theo[/name_u] for a girl, not [name_f]Thea[/name_f] or [name_f]Theodora[/name_f], just [name_u]Theo[/name_u]?
Blair
[name_u]Gray[/name_u]
[name_u]Lark[/name_u]
[name_u]Dove[/name_u]
[name_u]Rain[/name_u]
[name_u]Lee[/name_u]
[name_u]Haven[/name_u]
[name_u]Skye[/name_u]
[name_u]Arden[/name_u]
[name_u]Auden[/name_u]
[name_u]Sloan[/name_u]
[name_u]Ocean[/name_u]
[name_u]Arrow[/name_u]
Theo definitely feels way too masculine for me to consider it gender neutral. From your list, my favorites are [name_u]Kit[/name_u] and [name_u]Sage[/name_u].
Some other ideas:
[name_u]Riley[/name_u]
[name_u]Charlie[/name_u] (I know 7 letters but it feels pretty short)
[name_u]Remy[/name_u]
[name_u]Ash[/name_u]
[name_u]Sky[/name_u]
[name_u]Finley[/name_u]
[name_u]Jamie[/name_u]
[name_u]Quinn[/name_u]
Consider repeats as seconds!
Lior, [name_u]Owen[/name_u]/Olwen, [name_u]River[/name_u], and [name_u]Scout[/name_u]
I love all the names you have listed! I think [name_u]Theo[/name_u] would work. [name_f]My[/name_f] dad has a cousin named [name_f]Theodora[/name_f] “[name_u]Theo[/name_u]” but she has only ever gone by [name_u]Theo[/name_u]. It also makes me think of the character from The Haunting of [name_m]Hill[/name_m] House, even though she was [name_f]Theodora[/name_f] “[name_u]Theo[/name_u]” too, she only went by [name_u]Theo[/name_u].
Arlo
[name_u]Cove[/name_u]
[name_u]Adair[/name_u]
[name_u]Finn[/name_u]
[name_u]Flynn[/name_u]
[name_f]Jade[/name_f]
[name_m]Clark[/name_m]
[name_u]Hayes[/name_u]
I think [name_u]Theo[/name_u] works great for a girl!
Scout
[name_u]Blake[/name_u]
[name_u]Aspen[/name_u]
[name_u]Tate[/name_u]
[name_u]Poe[/name_u]
[name_u]Ellis[/name_u]
[name_u]Thames[/name_u]
I really like [name_u]Theo[/name_u] on a girl!
Lots of great suggestions so far, not sure if I have anything too add off the top of my head 
A few that haven’t been mentioned:
Avery
[name_u]Bowie[/name_u]
[name_u]Briar[/name_u]
[name_u]Casey[/name_u]
[name_u]Lyric[/name_u]
[name_u]Ray[/name_u]
[name_u]Reign[/name_u]
[name_u]Rory[/name_u]
[name_u]Wren[/name_u] / [name_u]Ren[/name_u]
Much prefer [name_f]Thea[/name_f] on a girl—[name_u]Theo[/name_u] feels all boy to me.
Max
[name_u]Rory[/name_u]
[name_u]Robin[/name_u]
[name_u]Sol[/name_u]
[name_u]Beau[/name_u]
[name_u]Lane[/name_u]
[name_u]Blake[/name_u]
[name_u]Indy[/name_u]
I love [name_u]Kit[/name_u] and [name_u]Sage[/name_u] from your list! I’m afraid I don’t love [name_u]Theo[/name_u] on a girl personally. Seconding the previous suggestions of [name_u]Lark[/name_u], [name_u]Skye[/name_u], [name_u]Arden[/name_u], [name_u]Riley[/name_u], [name_u]Finley[/name_u], and [name_u]Cove[/name_u]! Maybe:
Rune
[name_u]Wynn[/name_u]
[name_f]Greer[/name_f]
[name_u]Drew[/name_u]
[name_u]Lux[/name_u]
[name_u]Pax[/name_u]
[name_u]Echo[/name_u]
[name_u]Lake[/name_u]
[name_u]Snow[/name_u]
[name_u]True[/name_u]
Scout, [name_u]Wren[/name_u], [name_u]Bay[/name_u], [name_u]Brady[/name_u], [name_u]Echo[/name_u], [name_u]Hero[/name_u], [name_u]Minnow[/name_u], [name_u]Toby[/name_u]
I think I like [name_u]Theo[/name_u] for a girl
I’ve been loving [name_u]Reese[/name_u] lately.
I think Theo works on a girl, but only if it’s a nickname. I’m not really on board with just Theo for a girl. Suggestions:
Drew
Rio
Zion
Glade
Birch
Lee
Perry
West
Oak
Brook
Evan
Storm
Blaise
Aubrey
Bird
Ali
Jay
Jet
Bay
Vinnie
Ara
Cal
Neo
Day
Dusty
Glen
I’m sorry I don’t think [name_u]Theo[/name_u] works for a girl. It’s very boyish charm.
I get charlie ( I’m a [name_f]Charlotte[/name_f])
Other short unisex names I think could work are
[name_u]Billie[/name_u]
[name_f]Terri[/name_f]
[name_u]Leigh[/name_u] ( pronounced [name_u]Lee[/name_u])
[name_u]Jo[/name_u]
Theo for a girl is kind of cute
Noa
[name_m]Koa[/name_m]
[name_u]Scout[/name_u]
[name_u]Sloan[/name_u]
[name_u]Blair[/name_u]
[name_u]Pax[/name_u]
[name_u]Bo[/name_u]
[name_u]Lux[/name_u]
[name_u]Tate[/name_u]
[name_u]Flynn[/name_u]
[name_m]Archie[/name_m]
[name_m]Lio[/name_m]/Leo
[name_u]Rue[/name_u]
[name_m]Hart[/name_m]
[name_u]Beck[/name_u]
[name_m]Rowe[/name_m]
[name_u]Sky[/name_u]
I can’t think of any other names different from the great ones others have suggested but my initial though was [name_u]Beau[/name_u] or [name_f]Brynn[/name_f].
In terms of ‘[name_u]Theo[/name_u]’ for a girl I would personally only use it if the full name was [name_f]Theodora[/name_f], [name_f]Theodosia[/name_f] etc. I think its cute but too boyish as a stand-alone in my opinion. But go with what you love!
Alex
[name_u]Aspen[/name_u]
[name_u]Austin[/name_u]/Austen
[name_u]Brice[/name_u]/Bryce
[name_u]Chris[/name_u]
[name_u]Eden[/name_u]
[name_u]Jordan[/name_u]/Jordan
[name_u]Logan[/name_u]
[name_u]Max[/name_u]
[name_u]Pat[/name_u]
[name_u]Quinn[/name_u]
[name_u]Ray[/name_u]/Rae
[name_u]Riley[/name_u]
[name_u]Sam[/name_u]
[name_u]Wyatt[/name_u]
I like your names! I like [name_u]Theo[/name_u] for a girl but only as a nn, sorry. I’d like her to have the option of something that’s considered less boyish (unisex or feminine). Though I have included some more boyish names on the list so I kind of contradict myself lol.
Morgan
[name_u]Sawyer[/name_u]
[name_u]Rory[/name_u]
[name_u]Riley[/name_u]
[name_u]Reese[/name_u]
[name_u]Ellis[/name_u]
[name_u]Tegan[/name_u]
[name_u]Murphy[/name_u]
[name_u]Bailey[/name_u]
[name_u]Briar[/name_u]
[name_f]Brynn[/name_f]
[name_m]Covy[/name_m]
Though I prefer the names on your list to my suggestions (except [name_u]Rory[/name_u]!).
Maybe [name_u]Fox[/name_u] or [name_u]Lark[/name_u]?
Scout
[name_u]Hollis[/name_u]
[name_u]Briar[/name_u]
[name_u]Tatum[/name_u]
[name_u]Blaise[/name_u]