Output PDFs file size too big

As a photographer I have been using Bridge for over a decade. One of the most important ways I use it is to create PDF documents of low res (but good quality) images to show clients as contact sheets, often with one image per page. I found this to be a quick easy way to create a high res or low res PDF that can be emailed.

Recently with the new Bridge updates, the PDF sizes have become exponentially bigger - and therefore not possible to email. I never used to have to resize every image as the Output panel was very good at compressing and doing this for me and creating a usable file size. It is even creating large file sizes from small LR images. I don't know what has happened or if there is any solution to this, but my workflow is now incredibly slow as I try to compress and optimize PDFs in Adobe Acrobat which also is very glitchy and sometimes doesn't work at all. I'm now doing more work to try and do something I have done in Bridge for years and it's driving me crazy. I have already read the one post I found about this where someone suggested removing transparency option. I have already done this, and still the files are too big to email. For example, the images themselves (around 10-30 depending on job) together in MB make less than 15MB but as soon as I drag them into a PDF in Output panel, the file size will jump to over 100MB. This makes no sense to me - what information is it adding? I am also selecting a web size file at 1200x1600 px 72 dpi and high quality but not max which I have done for years. So why are the PDF'S SO BIG. Any help would be apprecaited as this used to just work well.