Hey there, Blubberykollis.
Have you remembered to disable the paging file? It could also be filled with a lot of System Restore points. Check out the suggestions from this link: http://www.howtogeek.com/125923/7-ways-to-free-up-hard-disk-space-on-windows/. It has an option which helps you analyze your disk space and this could make it easier to identify what might be filling up the drive.
You should also check out the tips for SSD users: https://www.maketecheasier.com/12-things-you-must-do-when-running-a-solid-state-drive-in-windows-7/. Those could save you quite some space and drive health.
Hope that helps.
Boogieman_WD