I would agree with other posters about resorts being pretty full already due to other discounts Disney has offered. I called first thing the morning the discount was announced last year for a Nov. date, and there was nothing available for CSR, and we ended up going with AKL and loved it, so it worked out. In the past we had not had problems with availability for fall, but that was before all of the other offers.
Stuff does open up though and people change their minds and plans, so keep trying. I called the day after it opened this year just to get some prices for Jan. and Feb. When I decided to book two day after that, another room category had opened that wasn't available two days before, which is what I had wanted. Maybe you'll end up at a different resort and it will work out well for your family anyway! Good luck!