There is a total of 17 Collectibles in Chapter 12: Dead Space. 9 of the Collectibles are Story-related (unmissable) and will unlock naturally.
Below the video you’ll find a full list of all Collectibles. The video covers everything that you need to collect which are missable. If you miss a physical Log, you can return later and pick it up.
Everything on the USG Ishimura (except Collectibles and a Trophy earned in Chapter 9) can be collected up until the point of no return in Chapter 11, except certain Logs triggered by certain actions in different Chapters. At the end of Chapter 11 you’ll be prompted with a dialogue box asking you if you want to leave the ship.