REAL REDUCING OF PDF SIZE

I tried all the online converters, Acrobat options for optimizing and so on... nothing worked and it took me 3 days.

However I have a amateur but working way to do it.

1. Print to PDF
2. Printer Properties 
1. "Default settings: Smallest file size"
2. Adobe PDF page size -> Add - and you make here a page size smaller than A4
3. Shrink oversized page