all the apps can't equal 950Gig... The data the applications "can" acess will fill that space, which can be moved to another drive.
this includes all pdf documents and illustrator files files, as some of them can be huge.
You can leave the application itself on the boot drive, but the files you open with them back be anywhere
best method is to get an external drive and move these drives to this external... That will be the only way to free up space on the drive.
An OS can only know about the its own free space. and any other partitions it can access.
If you have 2 partitions, by reducing one of them, you increase the other.... so you can increase your boot drive, and shrink the other one. '
If you don't have enough free space on the drive itself, an external drive is the only option.