How can I find my restore image on finder?

Well, I had updated my iPad to a beta version (9.3) and it was causing me trouble while trying to run apps from xcode.
So I unenrolled the beta iOS program from the apple website like I've been told to, and then created a local backup of my iPad using iTunes.
After that, I entered it into recovery mode and asked iTunes to update the iPad. Ok, downloaded the iOS 9.2.1 version, installed and everything seems to be ok until that moment... but when I tryied to restore from backup, there was no local backup showing on iTunes.
Well, my iCloud was last time sync at june, 2015... so, nope, no way... and my question is:

-where are the .ipsw restore files created from iTunes stored at? I think iTunes might not be seeing for some reason, but hope that its there yet! Once I find it, I should be able to restore...

Obs: Although my iPad has no extra apps on home screen (just the default ones from apple), on iTunes it shows that I have 29,1GB of stored data as "Other". (No jailbreak here, just checking..)