Maybe you can take another look at those numbers, they make no sense.
'19.5 mb and after packaging its about
2.5 Gb ’
Eh?
In any event, the way to get your package size down is to make a new empty project ( of your project type ), and then migrate everything you need to that project, and package from there.
All you have to do, in fact, is migrate the map. Because that will take everything needed with it.