NWjs still needs ALL of the NWjs requirements to run your exported project. It doesn't matter if your project files are 1Mb or 1Gb... NWjs will always make an additional 100Mb roughly to your export, because it has to include all of the NWjs runtime files to make your project work.
It's been explained 3 different times already in this thread - NWjs is 100Mb minimum, as it doesn't export to naitive Win32/64 EXE format. It's using a wrapper.
As Ashley said, why not just make it into a HTML5 export? It will then just open in any browser when you click the index file - and it will be tiny!
~Sol