For multiple reasons, including the intention of getting you to pay for “sponsored posts” Facebook only shows you about 15% of any of the posts of pages or profiles that you are subscribed to. It uses the near-mystical Edgerank formula to do this. However, a rogue link from the previous versions of Facebook still exists that may show you closer to 100% of the content you should see on FB. Sources say it will be shut down soon, though, as it was a remnant allowed to survive the previous versions of the social network for internal use, and not for you humans.
Put this URL into your browser and reload: https://www.facebook.com/?sk=nf_all