You can generally reduce a pdf smaller than the 'reduced size' version. Open your pdf in pro, choose 'save as other - optimized pdf'. Under images reduce the downsampling (if it says 72, try taking it down to 34). Make sure the jpg compression is set to provide the smallest files, make sure you're at least subsetting all fonts if they're embedded (and remove embedding if you can), set the transparency setting to low resolution, discard everything you can and etc.
Make sure you save with a different name and check and see if the quality is satisfactory for web viewing for previews (if the images were high quality to start with - it usually is). Play with the settings until you (hopefully) get what you like. It's also possible to save out a page with a lot of high res images, change the settings for that one, and put it back in.
This may not work for a magazine with a lot of pages, but it does sometimes help.
PS: You can also save all the pages out as lower res jpgs and then put them back into a pdf (or load them into InDesign and save out as a small pdf) and that will give you one file and save tons of room.
At the risk of stirring the pot even more, I feel a hypothetical example may help clarify my problem here. Let's just say, I'm the worlds greatest piano player* and I'm using Upwork to land some more gigs. I only charge 1,000 dollars per hour (a steal for the greatest in the world!) I've included some samples of the sheet music I use, pictures of my playing the piano, and even some of the wonderfull reviews I've recieved. So who wants to hire me?
* I can not play any musical instrument, unless the radio counts.