the ex-girlfriend bought one of these...
HP Stream 14-cb013wm, 14" HD Display, Intel N3060, 4GB RAM, 32GB SDD, Windows 10 Home S Mode, Purple
her machine shows that win 10 takes up 28 of the 32 G's
she had one program she runs to make tee shirts and the machine will now not even take updates as it is full.
the ssd and ram are integrated, can't be upgraded.
so something like this could be your problem.
could you tell us your computer model or stats, it helps.