Another Indesign issue... shrinking the file size

Hi, I'm trying to make my indesign file size smaller because I think it may be one of the reasons why I'm having issues exporting my book to PDF. The original file was about 800mb (360 page photo book). It was suggested that I open every photo and shrink the size to make the overall file size smaller. So I select one or more photos and control-click (mac), click open with photoshop, open the image size box (Image... image size) or option-command I and make the file smaller by reducing its height for example. My originals are NEFs that I converted into jpg and the original photo size is about 14x9 inches. I take it down to about 10x6 keeping it at 300ppi and using the Resample option of Bicubic Sharper (reduction). I got through about 140 pages of my book doing this and it appeared in the links panel of indesign that the file sizes were smaller (e.g. files go from about 10mb to a bit larger than 5mb. However, when I saved the whole document, the indesign file size was actually larger! It went from 800 to 840mb. Initially on saving the indesign file it was 1.2gb after shrinking the photos but I tried the save as option and that reduced the size, but ultimately, I'm not getting the overall file smaller by doing this. Is there something I'm doing wrong?

Thanks again.