Itunes took up a huge amount of space when restoring iphone.

I updated itunes recently and it deleted all of my music. So I had to spend quite a while redoing all of my playlists and music. To get all of this back on my phone I had to delete everything currently on my iphone. After I did this it freed up 12 gb of space. But when I tried to fill that space back up with my music and new playlists it told me that it couldn't because I had synced my phone with another computer, which I had never done. It then decided to fill that free space up with "other". So I had to then delete everything on my phone and restore from a backup.

After I deleted everything and went to restore it it told me I didn't have enough space on my computer. When I looked to see how much free space I had available I was shocked to see that I only had 14mb free. I'm not sure of the exact space I had left prior to trying the restore but it was at least 10gb. So I deleted a bunch of stuff I had backed up to give me about 6gb of free space. I tried the restore again only to get the same message. This time I had 1mb free on my computer. So I deleted 28gb of video files. This time it went forward with the restore but afterwards I had only 18gb of space free on my computer. The bottom line is that these restores filled my computer up with probably 25-30gb of space and I can not find where these huge backups are stored.

I tried deleting the old backups through the itunes preferences sections, but it only freed up less than a gigabyte. I did some googling and people are saying they are stored (on windows) in Username>AppData>Roaming>Apple Computer>MobileSync>Backup. But I don't seem to have that option on my computer.

I need to free this space back up and I am completely lost and pretty annoyed with itunes. Any help would more appreciated than you know.