CB1- Assur is the rong word.
I happen to own a sefer called “V’korey Shmoi B’yisroel” where its brought down from Reb Chaim shlit”a that all modern names (and Shira was one of them), are not names at all and that any one with those names needs to ad a name and be called by the new one only.
Also my wife knows someone named Shira who Reb Chaim shlit”a told to add or change (im no sure which) their name. And he told them to make a kiddush when they do so. The girl now goes by a different name.
You can see many of the names Reb Chaim shlit”a spoke about in this sefer many are popular names today adopted from Hebrew.
I would consult with a Rav if I where you.