Black Swan questions.

Is it just me, or is anyone else who has seen the movie black swan confused as to why that girl --The lead-- was delusional the entire film?

Movies such as that one I hate due to them being difficult to understand --their premises-- without aid. I went online and read about it, and have a vague understanding of the lead having those hallucinations throughout the entire movie due to being driven out of her mind from the pressures of her ballet involvement. Is that true? Is there more to it? What did you get from the movie? Did you understand the mentioned premise from observing the movie solely? After being "told" that's why she was experiencing what she did --like I had to be, if the information was correct?

I thought it was a great film, but not everyone appreciates symbolism. I never considered her character to actually be hallucinating herself turning into a swan. It was the directors way of showing us that she completely became the performance and character.