[name_m]Hi[/name_m] there.
I like your style! Here are my thoughts on your girls:
[name_f]Dorothea[/name_f]-This is beautiful. It’s strong, feminine, vintage & unique. I personally think that [name_f]Dori[/name_f] sounds kind of snobby, but that’s just my personal opinion. [name_f]Dora[/name_f] & [name_f]Thea[/name_f] are cute nns. And if you wanted to stretch it a bit, [name_f]Daisy[/name_f] for a nn works. I love [name_f]Daisy[/name_f]!
[name_f]Theodora[/name_f]-This is nice too. I think that [name_f]Dorothea[/name_f] is a little more unexpected. Especially since [name_m]Theodore[/name_m] is so popular for boys.
[name_f]Wilhelmina[/name_f]-This is lovely. Certainly vintage & clunky, but in a charming way. Lots of great nns! [name_f]Willa[/name_f], [name_f]Winnie[/name_f], [name_f]Minnie[/name_f] or [name_f]Mina[/name_f] are all great options. [name_f]Winnie[/name_f] is my favorite.
[name_f]Isadora[/name_f]-This is fine. I’m not sure why I don’t like it as much as the others. [name_f]Isabel[/name_f] & [name_f]Isabella[/name_f] are so popular, an [name_f]Isadora[/name_f] could get lost in the shuffle. [name_m]Just[/name_m] something to consider.
[name_f]Claudia[/name_f]-I don’t mind this name, but it doesn’t sparkle as much as the others.
[name_f]Henrietta[/name_f]-This is different. Maybe a little too clunky for me personally, but the nn [name_f]Hattie[/name_f] is adorable.
[name_f]Dorothea[/name_f] & [name_f]Wilhelmina[/name_f] are my favorites. I bet if the little one comes out a girl, she’ll tell you her name. 
Here are some boy suggestions:
[name_m]Alfred[/name_m]
[name_m]Arthur[/name_m]
[name_u]August[/name_u]
[name_m]Augustus[/name_m]
[name_m]Bernard[/name_m]
[name_m]Barnaby[/name_m]
[name_m]Barnabas[/name_m]
[name_m]Bastian[/name_m]-I like this more than [name_m]Sebastian[/name_m]. It’s sleeker & more unique.
[name_m]Desmond[/name_m]
[name_m]Edward[/name_m]
[name_m]Frederic[/name_m]
[name_u]Laurence[/name_u]
[name_m]Peter[/name_m]
[name_m]Percival[/name_m]
[name_m]Peregrine[/name_m]
[name_u]Sullivan[/name_u]
[name_m]Solomon[/name_m]
[name_m]Winston[/name_m]
[name_f]Hope[/name_f] this helps. 