Altough this doesn't fully address the question, in order to free up some space I suggest you to first remove the installed packages that are not needed anymore:
sudo apt-get autoremove --purge
Then you can clear the
/var/log folder, which is extremely prone to grow in size over time, expecially if something at some point didn't work perfectly:
sudo rm -rf /var/log/*
Then you can use this command to list all your files/folders sorted from the smallest file/folder to the biggest file/folder, in order to quickly spot which files/folders are the biggest so you can possibly free up some additional space:
du -ahd <n> / | sort -hr
<n> is a number higher or equal to
0 representing the depth of the search.
3 should be a number large enough to narrow down the search a bit without having to deal with an excessively large list of files/folders.