startup disk is full but it isnt

I've been having this problem for a while now. My Mac will tell me my hard drive is full, but it's not anywhere near full. Everytime it has I've just deleted some stuff, emptied my trash, and deleted free space with disk utility. This usually makes the problem go away for a while but this time I did it, and I was only left with 14 GB left. I don't know how I'm filling up my hard drive without putting anything on it. I've used multiple different scanning software to see if my hard drive is really that full but each one says the same thing. I put a Screen shot of one of them(OmniDiskSweeper). The software scans hidden files and folders too, so don't just tell me that it's a hidden folder. I was looking around and someone said they had a similar issue and they found that it was a hidden volume, but I have my finder setup to see all hidden files, folders, volumes, etc. but I dont see any volumes other than Macintosh HD, Home, and Net. I looked up what Home and Net were and they're for mounting DMG files when you download something. I've done so many different things like Emptying my trash, using Disk Utility to repair disk and repair permissions, Erased free space, and I've even went through every single file on my computer manually to see if there were hidden volumes(RIP 5 hours....). Also when I look at how my hard drive's usage is divided, 463.77 GB is being used by "Other" and I cant figure out what that is. Can somebody please help?