Bump and Me plus Three

So as I said in my previous post about speech delay bump is now 4 and still not potty trained, I started off potty training at 2 and its just been a struggle ever since, I feel like I've hit a brick wall and I just don't know what to do anymore. he wont sit on the potty or the toilet, have tried everything to encourage him, books, dvds haven't tried a reward chart because he would have no interest in that.  Took his nappy away but he will just wet or pooh himself and not care. He wears a nappy to nursery and he is due to start reception in September, what am I going to do send him to school in a nappy? I cant do that, I'm hoping and praying he's just going to decide to do it on his own but he is quite happy still wearing a nappy with no prompt to change him if he's done a pooh. I'm at a loss and feel like a total failure, I've potty trained his sisters perfectly fine so why cant I do it? please feel free to leave me a comment, email or tweet me i...