The "Other" tab on my HD keeps filling up even after i delete stuff from it

Question

Hi! Just wanted to share my story to see if any of you knew about this and how to solve it, because it's driving me insane to the point where i want to throw mi macbook out the window.
So, i have a MacBook Air (11-inch, Mid 2011) with a 64GB HD. It's not a lot of space, but i really just use my computer for really basic stuff. I never had any problems with its storage capacity up until two months ago, when it got super slow. I got rid of a lot of files i had not used since college, but i began to notice that the "Other" tab on my HD kept taking up more and more space. This is still happening by the way, to the point, where i now get a message saying that my disk is full. I already tried everything: CCleaner (super useful the first time i used it; not so much the second time), i tried to use a time machine back-up (which showed results for two days but then it went back to where it was), and today i resorted to something I did not want to do: I MOVED MY ITUNES LIBRARY TO AN EXTERNAL HD. I was hopeful this would help me, after all, 10 GB of space suddenly freed up would give my computer a needed breath (working on it for the last week or so has been a nightmare: it's going super slow, it gets hot just by using Safari, etc). So i did this, i erased my music files from my hard drive and then i saw how those "10 GB" which i was supposed to get back in free space were now taken by the "Other" tab, which went from 33 GB to around 44 GB (See image - everything is in spanish but you get the point).
So...my question is: What else can i try? I tried to restore my computer to factory settings but it told me i needed at least 10 GB of free HD space. By the way, i'm new to Yosemite, having recently installed (like two weeks ago...right when things really took a turn for the worse). Any recommendations are welcomed!!!

Answer 1

For information about the Other category in the Storage display, see this support article. If the Storage display seems to be inaccurate, try rebuilding the Spotlight index.
Empty the Trash if you haven't already done so. If you use iPhoto, empty its internal Trash first:
          iPhoto ▹ Empty Trash
Do the same in other applications, such as Aperture, that have an internal Trash feature. Then restart the computer. That will temporarily free up some space.
According to Apple documentation, you need at least 9 GB of available space on the startup volume (as shown in the Finder Info window) for normal operation—not the mythical 10%, 15%, or any other percentage. You also need enough space left over to allow for growth of the data. There is little or no performance advantage to having more available space than the minimum Apple recommends. Available storage space that you'll never use is wasted space.
When Time Machine backs up a portable Mac, some of the free space will be used to make local snapshots, which are backup copies of recently deleted files. The space occupied by local snapshots is reported as available by the Finder, and should be considered as such. In the Storage display of System Information, local snapshots are shown as  Backups. The snapshots are automatically deleted when they expire or when free space falls below a certain level. You ordinarily don't need to, and should not, delete local snapshots yourself. If you followed bad advice to disable local snapshots by running a shell command, you may have ended up with a lot of data in the Other category. Ask for instructions in that case.
See this support article for some simple ways to free up storage space.
You can more effectively use a tool such as OmniDiskSweeper (ODS) or GrandPerspective (GP) to explore the volume and find out what's taking up the space. You can also delete files with it, but don't do that unless you're sure that you know what you're deleting and that all data is safely backed up. That means you have multiple backups, not just one. Note that ODS only works with OS X 10.8 or later. If you're running an older OS version, use GP.
Deleting files inside a photo or iTunes library will corrupt the library. Changes to such a library must be made from within the application that created it. The same goes for Mail files.
Proceed further only if the problem isn't solved by the above steps.
ODS or GP can't see the whole filesystem when you run it just by double-clicking; it only sees files that you have permission to read. To see everything, you have to run it as root.
Back up all data now.
Install the app in the Applications folder as usual. Quit it if it's running.
Triple-click anywhere in the corresponding line of text below on this page to select it, then copy the selected text to the Clipboard by pressing the key combination command-C.
For ODS:
security execute-with-privileges /A*/OmniDiskSweeper.app/*/M*/* 2>&-
For GP:
security execute-with-privileges /A*/GrandPerspective.app/*/M*/* 2>&-
Launch the built-in Terminal application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad and start typing the name.
Paste into the Terminal window by pressing command-V. You'll be prompted for your login password.
The application window will open behind other open windows. When you scan a volume, the window will eventually show all files in all folders, sorted by size. It may take a few minutes for the app to finish scanning.
I don't recommend that you make a habit of doing this. Don't delete anything as root. If something needs to be deleted, make sure you know what it is and how it got there, and then delete it by other, safer, means. When in doubt, leave it alone or ask for guidance.
When you're done with the app, quit it and also quit Terminal.