The iMac version of the save game bug?

[The Troubadour]

Hi all, I apologize if this is a common question here, I've taken a cursory glance but most fixes describe PCs.

This could be the game or it could be my computer. It's a 6 year-old iMac that claims to have insufficient graphics for the game, though it's been mostly just fine.

However, as many of you will have experienced before, after quitting the game and starting it again, the last 10 days of progress are gone, and save games only exist form Chapter 3 on. I'm not extremely computer savvy, and a cursory search for the Steam folder couldn't find a folder with save games, though I may not be looking in the right place.

Is there something I can do? Ideally for the save games I've already "lost"?

Anyways, thanks!