Why is my internal storage full if I dont even have any apps that is big im usibg a Huawei GT3 As shown in the picture below:


Storage (click for larger image)
I recommend you to reset your phone from FACTORY DATA REST 
To reset your phone from factory data reset 


  Go to settings>Backup and reset>factory data reset>RESET PHONE


I have also experienced this problem in my Lenovo A2010 
Probably I had used only 500mb out of 4GB but then also only 200mb was available.
After factory data reset the problem was solved and 2.5GB was available...

NOTE:-Before resetting you should backup your data on SD card and remove SD card and sims from your device before resetting.