Why is my storage so messed up? q-q

[ItsVexonix]

So a few days ago, I tried downloading FIFA 15 Ultimate Team on my phone (A Moto E) and the download stopped at about 98% and said 'There is insufficient space on this device' So I really wanted the app, so I went to go delete some apps and it said that I only had 100 something mb of storage left, although prior to the download I had 1.3 GB of storage, because FIFA is 1.2 GB and I wanted some excess storage for things such as updates. However, if you add up the apps, videos, etc, and subtract it by my device memory to find out how much storage I have left, does NOT equal the same in any way. It says I have 136 MB left, however when you add up everything that I have on my phone, I'm only using about 900mb of storage. My phone has 2.17 GB of internal storage, and 2.17×1024 equals about 2048MB of internal storage. 2048-900 does NOT in any way equal 136 MB of storage left. If anyone could help, I would very much appreciate it. Thank you!

 

[anon(5600632)]

Did you clear the cache? Settings-storage-cache.

 

[ItsVexonix]

Yes, I just tried it once again and now I have a new error. I have attached a screenshot showing my error.