Try checking the cancellation thread on here for the month you are going. If you haven't been on it before, go under the dining forum, and go to the Reservations category, and you will see that there is one for each month. People will post if they are going to cancel an ADR, and you can PM them to see if you can coordinate when they are canceling, so you can try to pick it up. You can't ask for what you want, but you can keep checking to see what comes up for your dates. I have been able to pick up ADRs on several trips this way, and have been able to post my cancellations, and help someone else. I also agree with PPs to keep trying, and you will find something. I had to move our trip for last Nov. to the week before Christmas at the end of Sept., losing all my 180 day work. I managed to get everything we wanted, even the hard to come by Minnie's Holiday Dinner(and BOG lunch!)
Edit - just realized I had only read page 1 when I posted, so sorry if this advice has already been given! Also see, you are already there, so hope you got it!