I wouldnt give up. Something always opens up. Keep checking. Even while youre at WDW, get concierge to check daily....even Guest Services at any park. Your bound to get something. i've always been successful!
Don't give up! We got our first CRT ressie on fairly short notice - I just kept calling every day (this was before the online system). Even try once you're there, especially around the deadline for folks to cancel without losing their deposit. Good luck!