I'm a Windows 7 Professional edition user, I might be able to help some.
What are your System Restore Points percentage set to? You might start there by vastly reducing the amount of byte-space SRPs are given. You are making routine OS and Data partition full image backups onto external media of your choice, correct?
It is possible that some or all of your security and monitoring programs, whether foreground or background, are writing logs, writing logs, writing logs. Get into each one and reduce log-writing. Eliminate other log-writing that is not needed or wanted.
Be very careful about "shrinking" or "reducing" programs, services, startups, which belong to Windows Prime. Consider uninstalling and/or reducing the "footprint" of some of your 3rd party programs and utilities.
It just might be time to purchase a larger SSD for your OS and 3rd party programs, and a 2nd HDD for all your data folders and files. If monies are a problem, then, begin with the house-cleaning steps mentioned above.