iTunes recognizes my phone but won't sync?

This morning, I tried to sync my iPhone 5S with my iTunes because I'd made some new playlists that I wanted on my phone. It wouldn't do it and for some reason I think that I thought that space was the issue, so I deleted all my music off my phone (from my phone), assuming that I could just sync it back up, no problem. Now, my iPhone only has the songs that I've purchased through iTunes, and not the 530+ songs I have downloaded, and I just cannot get it to sync.

It recognizes my phone just fine. That's not a problem.

I've already tried everything that I can think of, as well as following as many online guides I can find.

I've tried:

-Restarting iTunes, my computer, and my phone.

-Messing with music sync options in iTunes, trying to sync select songs and albums manually, or disabling and enabling auto-syncing.

-Deauthorizing and reauthorizing my computer.

-Enabled wi-fi syncing, my iPhone doesn't recognize that my computer is in fact available and won't let me sync anything.

-Changing USB ports and USB wires. I have 3 cords and 3 ports, they're all doing this.

-Updating everything on my computer, making sure that iTunes is up to date (it is), and updating my iPhone to 9.3.1 (was on 9.3)

-Checking my Portable Device drivers to see if it was up to date (it was)

-Ending all processes having to do with iTunes, renaming the sync folder in appdata, and restarting iTunes. Did nothing.

The sync button is grey and won't let me click on it. In my space used/available bar it says everything I'm using is "other." Under "On My Device" in Music it still says I have 534 songs even though, on my phone, it only says I have 3 albums (the stuff that I've bought from iTunes). Additionally, after I deleted all my music the space available dropped down from 1.something gb's to 3.76, showing that there is more space on the device from where I deleted everything. (I'm on Windows 8.1, by the way.)

Additionally, when I try to create a backup to this computer, it does nothing and says that I've never backed up this iPhone to this computer (which I have)

I haven't uninstalled/reinstalled iTunes or reset my iPhone. I'm posting here in the hopes that I won't have to do that.