Horror film narrative

For our film we decided to make a film that was based around a character who is suffering from hallucinations but what is coursing them (whether it be supernatural or insanity) is not clear.

The story is of our character (Ella) trying to find out what is the reason for her hallucinations because she thinks it has something to do with her past but she can't remember and others think that she is just insane. All she can remember is that she broke out of a mental institutions and that the authorities want to take her back but that she but also that she must not go back for reasons she doesn't remember.
Another aspect of the film is that she also suffers from paranoia and is and her hallucinations get more terrifying and real to her leading her possibly losing her mind. There is also someone who is interested in her but who this person is and why they are is a mystery and is connected to trying to take her back to the mental institution.
The film is of Ella as she ties to find out the reason for her hallucinations while avoiding anyone who ties to take her back.
We also talk about her have a male character who wants to help but it would not make it into the opening of the film so doesn't need as much character planing as Ella.