iPad mini is showing music that is not selected.

I have an iPad Mini that is attached to my Apple ID but is used by my 3yr old son. I have selected only 3 playlists for music he likes to appear on his iPad. I am noticing that its also showing ALL of the PURCHASED music I have bought over the years that are in my iTunes library which is well over a thousand songs. When the iPad is connected to my iMac via the USB cable and I go to look at the Music Tab. I have Only Music from Selected Playlists checked off and checked boxes for each playlist I WANT to sync to the iPad. The check box for Purchased music is NOT checked however all the purchased songs keep appearing on the iPad Mini and I am sure that is eating up space considering its a 16gb iPad Mini and he only has 3gb left! There is no way the little bit of content that is on there is eating up that much space.

Any thoughts?