[name_m]How[/name_m] about:
[name_f]Adeline[/name_f] [name_f]Thomasina[/name_f]
[name_f]Juliet[/name_f] [name_f]Thomasina[/name_f]
[name_f]Rosalind[/name_f] [name_f]Thomasina[/name_f]
[name_f]Guinevere[/name_f] [name_f]Thomasina[/name_f]
[name_f]Ivy[/name_f] [name_f]Adele[/name_f] [name_f]Thomasina[/name_f]
[name_f]Stella[/name_f] [name_f]Irene[/name_f] [name_f]Thomasina[/name_f]
[name_f]Viola[/name_f] [name_f]Thomasina[/name_f]
I think most of the names that I would suggest have been mentioned already…[name_f]Cecily[/name_f], [name_f]Iris[/name_f], & [name_f]Juliet[/name_f]. Perhaps Rosabeth? I don’t know if you’d consider the [name_f]Tamsin[/name_f] form of [name_f]Thomasina[/name_f], which would provide a different sound while keeping the same meaning. Good luck! 
I’m sure most of the names I would suggest have also already been mentioned, but what about:
[name_f]Aurora[/name_f] [name_f]Thomasina[/name_f]
[name_f]Elowen[/name_f] [name_f]Thomasina[/name_f]
[name_u]Fable[/name_u] [name_f]Thomasina[/name_f]
[name_f]Fawn[/name_f] [name_f]Thomasina[/name_f]
[name_f]Freya[/name_f] [name_f]Thomasina[/name_f]
[name_f]Helena[/name_f] [name_f]Thomasina[/name_f]
[name_f]Luna[/name_f] [name_f]Thomasina[/name_f]
[name_f]Maple[/name_f] [name_f]Thomasina[/name_f]
[name_f]Meadow[/name_f] [name_f]Thomasina[/name_f]
[name_f]Oona[/name_f] [name_f]Thomasina[/name_f]
[name_f]Opal[/name_f] [name_f]Thomasina[/name_f]
[name_f]Rosamund[/name_f] [name_f]Thomasina[/name_f]
[name_u]Vesper[/name_u] [name_f]Thomasina[/name_f]
[name_f]Winifred[/name_f] [name_f]Thomasina[/name_f]