If an item is not in your installed content tab, there is only one thing you can do and unfortunatly it's quite a hassle:
You will need remove all *.dbc files from your launcher. All your downloads except store/houses/sims will be gone. You will then need to reinstall everything that you want to keep. If you still have all your downloads in the download folder you can just reinstall by clicking install in the download tab.
Make sure to check houses/sims beforehand and for the doll basically everything. Start your game with a new test game to see if really everything is gone before you reinstall your downloads. Don't start the normal game for then all your the stuff you used will be replaced.
I would not install all in one go but install a few and then go back to the test game to see, if nothing bad has gotten installed.
I've added the tight arm dress to my list.
