The “autobundle” command for CPAN will help with what’s installed but if you installed with the package manager that’s probably as good a place to start; however it’s possible you’ve possibly gotten your Perl install into a state it (CPAN) may not run.

This kind of wonkiness is why if you’re doing anything serious with perl it’s going to be much more controlled (by which I mean under your control) to make a separate install from the OS’ (using perlbrew or from source) and only install after-market modules into that copy (and/or a local::lib dir) using CPAN (or cpanp or cpanm) rather than being subject to the package manager’s whims.