Writing your EPQ on autism could be a good idea, but I would argue that writing it on "The Reason I Jump" may not be. The claim that it was written by an autistic child is really only true from a certain point of view, as it's really written by his mother based on interpretations from his very limited ability to communicate. It's been criticised a lot for reading like wish fulfillment on her part and not being accurate to what autistic people actually experience. The translation over to English also introduced a lot of generalising statements (e.g. we do this because...) which were not in the Japanese original (which claimed to only speak for the boy's own experiences) and a lot of what it says disagrees with almost everything else on the subject, such as assuming autistics can be particular about food due to not being able to taste certain foods, rather than the general agreement that it's due to being overly sensitive to the texture.
There are books which have been definitely written by autitistic adults in English, and from those I'd most strongly recommend the works of John Elder Robinson and Temple Grandin. Robinson's work comes entirely from an asperger's perspective and he has lived an overall quite successful life, from repairing equipment for bands to running his own car repair business. Temple Grandin started off quite low functioning and wasn't able to talk until the age of four, but is now a respected professor of animal science, lifestock consultant and author. You're not going to be getting anything directly from an autistic child from either of them but their books do go back into their memories of childhood, and Robinson has written ones on raising his autistic son.
It's also worth looking into the informative literature on the topic in addition to the stories, such as Tony Attwood's "The Complete Guide to Asperger's Syndrome". This book is also more focused on the high functioning end of the spectrum but is very informative. You can also look into a lot of information online and perhaps look at the Wrong Planet forum to get perspectives directly from autistic people.
In any case, I wouldn't recommend writing on "The Reason I Jump" unless you combine it with other, less dubious works on the subject, as you're otherwise going to be getting something very distant from the reality for most people. That's my perspective, at any rate, as someone with autism/asperger's. On that note, if you have any questions about autism, I'd be happy to answer them or point you towards something that can.
Good luck with your dissertation, whatever you decide.