[App 9.1][PT 8.53] Best Way to Detect Customizations

Unfortunately we didn't have a habit at one point of maintaining an upgraded DMO database so we can't compare it, PUM style, to our actual database to identify customizations (e.g., adding a field to a page).

What's the easiest way (other than the above) to detect customizations? Can I query the metadata to see if we're the last source of a change to each object? Is there some other way with change assistant? Thanks!