itunes sync is extremely larger than expected

Hello,

I have a 32 GB iPod Touch, 5th generation. (iOS 9.0.2) Today, I attempted to sync my iPod touch (no new songs or apps have been added since my last sync) and iTunes gave me a pop-up notification (shown below). which is absurdly larger than the sync that I am using right now. The only thing that has changed since the last sync was the fact that I changed the ratings on ~40 songs or so, but that's it. The current sync on my 25.12 GB, and the capacity of the attempted sync (from the pop up shown below) is roughly the size of all the remaining music that isn't synced to my iPod. I have the box labeled "sync only selected songs" as well as selectively syncing music using the check boxes in the "iPod"->"music" tap.

Here is a screenshot of the statistics on my entire iTunes music library (shown in the bottom center of the window)

I even tried unchecking ~1.5 GB of songs, but I still got the same exact popup. I was expecting to see the over capacity amount drop by 1.5 GB, but it stayed exactly where it was before. Could I somehow be syncing the wrong device, or somehow attempting to sync the entire library (even though I have used the custom check boxes as described above?)

Basically, I have been selectively syncing music for a long time without any problems. Now, I have a pop-up that is telling me that I'm extremely over capacity, even though I haven't changed anything. Was there a software change that might be causing this?

Thank you for your help, let me know if you require any other information (or if I should post this question elsewhere to get it answered more accurately)

Best,

Jake