Hello
Not sure why I am posting, but maybe if I write out what I am struggling with I can work out where I am going wrong and find a solution. If anyone writes a reply, its a bonus - and thank you in advance if you do 
I am trying to turn a short story into a novel. I wrote the short story (400 odd words) a while ago, and its just been sitting there doing nothing.
Now that I am trying to "fill it out" I am struggling with the finer details of the character, where she has come from, what she is going through. I can't even decide her age! She stared off at 11yo, now I am thinking she should be 17. Her voice has become too mature for an 11 year old child. In fact her voice has started to become very muddled. Perhaps I should consider third person.
I can't even work out what era she is living! Or whether she goes to school or not (truant? or was never registered with a school - i.e. her parents kept her indoors, as a sort of secret child - is this even possible? And if so, where does her beloved grandfather come into it?)
In the short story, her late grandfather was her rock, the only person who loved or understood her - but then again, if that is so, why would he allow her to be treated in the way her parents treat her?
I honestly feel like completely giving up 