th3m4dha77er If you've installed and are now launching Sims 4 through Steam, your game will be loading that version, and that version doesn't have your packs installed. So either go back to using the EA App version; or uninstall the game through the EA App, restart your computer, and download only the packs you own from the EA App, not another copy of the base game. The packs should then install into the Steam version of the base game, from where they should load properly.
Once you've reinstalled, check Marketplace > My Collection to make sure the packs are activated.