After updating to iOS 5, my most recent backup is gone! HELP!!

The iPhone update began Wednesday night; before starting, I attempted to do a backup a few times, and it failed. As the update began, the backup refused to work then as well. After a couple attempts with errors, I checked the list of backups in "Preferences" to see when the last backup was recorded. It said "yesterday," which wasn't too far back, so I let the update skip the backup, intending to let my phone restore from the prior day, should it need to.

Later, when iTunes asked me to select a restore, the one from the prior day was missing. The latest backup showed June 22. I let it continue, just wanting to have my phone in a functional state, but somehow hoping that it had it wrong, that it was actually the more recent backup. After following the iOS 5 setup steps, I checked my text messages - and it showed the last texts were from June 22.

A little upset, but not yet giving up, I found the hidden folder where backups were stored. The latest files were also from June 22.

I also checked the Recycle Bin, which contained an .ipsw file. It had the word "restore" in the file name ("iPhone2,1_4.3.5_8L1_Restore"), so I attempted to use it to restore my phone to its prior state by holding down SHIFT while clicking the restore button in iTunes (a Google search led me to this). After 9 attempts at this, I gave up, and brought my phone back to factory settings temporarily, so I could have a working phone before going to school. I found out afterwards that the file was only an operating system file and contained nothing of my former settings (even though one forum claimed to have found their actual backup located in the Recycle Bin in a similar situation).

I'd very much like to have all my recent text messages, etc. back on my phone. I usually backup my phone pretty regularly, so the fact that the "most recent" one goes all the way back to June is positively bewildering. This is really ruining my experience with the new iOS, and my phone in general.

Why is my recent iPhone backup missing, and how can I get it back?