File Size

I have an illustrator file that in total is about 1.9 mb. However i have linked (not embedded) 7 images. These images total 5mb. This would add up to a little over 7 mb one would think. However when i hit save, my illustrator file jumps right to 72.3mb. i need to save as a pdf to send before it gets sent to print. How... Where is this 60+mb coming from? I unchecked the "save as compatible pdf" box, which dropped my illustrator file to 32.5mb, however when i saved THAT as a pdf, it goes right back to 72.3mb. What am i doing wrong? i do not get it. im losing my mind over this invisible 60mb. Its a clean brand new file.. no hidden layers, no effects, all vector work + 5mb of images.

Thank you for your help, im sure its something simple im overlooking.