The storage space on my MacBook Pro does't add up
I am running out of space on my MacBook Pro, so I decided to look and see where all my storage is going. I found the space on my hard drive (250 GB) and then manually checked each directory for the space it is using. It comes up to around 10 GB less than what it should be. I took my free space into consideration. This seemed strange, but within reason.
I then decided to check my user directory which shows 126.08 GB used. My ID uses 125.6 of this, so I checked every folder and file in this directory. I can only find around 50 GB of files in this directory which means that around 70 GB is missing. The amounts for each subdirectory seem about right if I look at its contents.
I keep my iTunes and pictures on an external drive, so my hard drive should be pretty small. Does anyone have a clue what is going on?
Mac Pro, OS X Yosemite (10.10.2)