It seems like it would be easier for her to just say her nn is Lulah as opposed to going through the whole name change process. Saying your name is
Tallulah but you're called Lulah doesn't seem much different than saying your name is
Jennifer but you're called
Jenny. Plus, I question allowing a child to make that decision at age 13. Lord knows what I might have chosen to name myself at 13, but, whatever...