backing up iPhone in iTunes. Where does Backup go?

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I am backing up wife's iPhone to iTunes (using her OS X account) and iTunes says it finished backup, but iTunes folder is only 3.8 MB (Mega Bytes) and she has about 14 GB of stuff on her iPhone (capacity 28, available 14).

This can't be right.

EDIT: iPhone 5, iOS 10.3.3, OS X 10.9.5, iTunes 12.6.0

EDIT 2: apparently they go here

~/Library/Application Support/MobileSync/Backup/

I think they used to go into iTunes folder a while back... but I am not sure. Now where can I find the Apps? I want to manually move one App from her old iPhone to new iPhone.