Creating small pdf with high quality graphics

Hello everyone

I am currently working on my portfolio and other book(let) documents with a high range of drawings in (dwg). I import my drawings as pdfs in my file, but when I convert indd to pdf I get insanely big files. I also tried to solve this by converting my pdfs to a png or jpg file in illustrator, but when I try to convert the indd to pdf then I get a ****** quality in my graphics (although I use maximum quality of compression and 300 dpi). Any solutions?

Thanks in advance.

following pictures should illustrate the problem