Note the question was reopened but now it's been closed again for being opinion-based. Yet the OP's words "what would be the best/correct way" are equivalent to "what are the grammatical rules behind these two options". The question should once again be reopened.
As to one person's constant chiming that the question shows no research, that is not true. The research was presented by the OP in the very first version.
The question "A" or "The" in a title was closed when the body read:
What would be the best – correct way to pick for a title of a project: A girl who wanted to be a boy
Or
The girl who wanted to be a boy.
Google books shows both versions
Subsequently, the OP has added 369 words to the body of the question that give enough detail to afford informed answers. (As an aside the hyperlinks were also cleaned up in the editing process.)
Subsequent to that substantial edit the OP posted another ~500 words of story summary in a commenta comment, since deleted.
Note closing the question seemed to come about after one closevote, after which one moderator closed it.
For those who don't think the question should be reopened, please explain why not. (I assume the DV to this meta-question was given for that reason.) And say what else can be done to clarify the question?
It seems to me an interesting question about the use of definite vs indefinite articles in the title of stories/novels, as opposed to the run of the mill-of-the-mill query about lack of articles in headlines.
The OP went to the trouble of including their own research.
