Need advice as have concerns about my daughter.

Hi, I thought I'd come here to ask for advice from other parents.  My eldest daughter is 8 yrs old, she will be 9 in Feb.  She  has had no particular health problems, in fact pretty robust constitution. there are a few things however, which cause me concern and have tempted me to question if she has some form of autism.  The biggest thing is her lack of progress in reading/spelling/writing in school as compared to her peers.  We have had her eyesight checked and her hearing checked.  In 2009 her hearing test showed below normal but just recently it was fine.  Since nursery she has chewed/eaten non food stuffs, plastic pegs, paper, chalk, bluetack etc, her favorite being paper.  I have watched her deliberately seek out or go for paper and sneak a tear off and either conceal it or put it in her mouth, (if she thinks no-one has noticed). She acts very immature compared to her peers, she will make strange noises, does funny moves and becomes quite hyper.  She doesn't play games with us as a family in the same way her little sister does.  Her younger sister focuses, pays attention and works out the strategy, DD1 doesn't sit still, always fidgeting.  She is very easily distracted, very giggly, tends to have wetting accidents when laughing.  I have made an appointment to have her assessed at Jordan's Eyes in Ayr, partly to rule out dyslexia or the need for colored lenses, but they also look at the autistic spectrum.  Regardless of the outcome I just want to know we are doing all we can for her.  I'd appreciate anyone's views/thoughts on this.

Thanks