my Windows folder (Win10) takes up 25.5GB's, so your 23GB is about right.
the the 3 Program Files folders add to 10.5GB.
so there's your 30GB blown without even thinking about anything personal let alone room to grow.
look into turning off or reducing your pagefile, hibernation file, Recycle Bin size, Restore Points allocation etc.
check you have no Windows.old folder, if so, remove it with the inbuilt cleanmgr program from an elevated command prompt.
get and run CCleaner from here;
https://www.piriform.com/ccleaner/builds [/font]and see how much space it reclaims.
but in short, 30GB was never going to cut it and you would have eventually been in this predicament at some time.