Weird external hd question

[05caddyext]

I have a Seagate 3TB external hd. It says it's almost full, I have 158 GB of free space out of 3TB. I literally can't find more than 1TB of files on it. How the hell do I find what's causing it to be nearly full? I ran disk clean up, it only found like 3gb of files in the recycle bin. Any ideas?

[Yooformula]

did you check hidden files?

[05caddyext]

found the stuff. it was auto backing up everything everytime i saved a new file. it would backup evrry single file. i really have about 150gb on it it saved 2.5TB in backup info.