How sweet of your mother!
I guess you could use a phonetic spelling of [name_f]Saoirse[/name_f], i.e. Sirsha or Seersha.
A few others (anglicised) [name_m]Irish[/name_m] names to consider: [name_f]Enya[/name_f], [name_f]Grania[/name_f], [name_f]Cliona[/name_f], [name_f]Elva[/name_f], [name_f]Moira[/name_f], [name_f]Orla[/name_f], [name_f]Neve[/name_f].
More ideas (the first list consists of fairy or fairy-adjacent characters from folklore and popular culture while the second is a random assortment of fairy-like names):
[name_f]Melusine[/name_f]
[name_f]Gloriana[/name_f]
[name_f]Alcina[/name_f]
[name_f]Viviane[/name_f] - the same character is also known as [name_f]Vivian[/name_f], [name_f]Nimue[/name_f], [name_f]Nivian[/name_f], [name_f]Ninianne[/name_f] etc.
[name_f]Mab[/name_f]
[name_f]Lorelei[/name_f]
[name_m]Puck[/name_m]
[name_m]Oberon[/name_m]
[name_f]Titania[/name_f]
[name_m]Marinell[/name_m]
[name_f]Oriane[/name_f]
[name_f]Nixie[/name_f]
Holda / [name_f]Hulda[/name_f]
[name_f]Iolanthe[/name_f]
Étaín
[name_m]Morgan[/name_m]
[name_f]Petronella[/name_f]
[name_f]Elfie[/name_f]
[name_f]Thalie[/name_f]
[name_f]Lumina[/name_f]
[name_f]Belphoebe[/name_f]
[name_f]Amorette[/name_f]
[name_f]Corinna[/name_f]
[name_f]Feather[/name_f]
[name_f]Echo[/name_f]
[name_f]Lavender[/name_f]
[name_f]Bluebell[/name_f]
[name_f]Willow[/name_f]
[name_f]Laurel[/name_f]
[name_f]Madrigal[/name_f]
[name_f]Diantha[/name_f]
[name_f]Melisande[/name_f]
[name_m]Lazuli[/name_m]
[name_m]Zephyr[/name_m]
[name_m]Gale[/name_m]
[name_f]Nolana[/name_f]
[name_f]Celesta[/name_f]
[name_f]Poem[/name_f]
[name_f]Eglantine[/name_f]
[name_f]Lilienne[/name_f]
[name_f]Nydia[/name_f]
[name_f]Dianella[/name_f]