I'm just completely confused about updating my game. Help please!!

So I have only the base Sims 3 game and the High End Loft Stuff pack installed.

When I go to the updates tab it tells me to start my game and then use the update tab. So I go start my game and then use ctrl alt tab to go back to my desktop. I pull the launcher back up and go to the updates tab. But then it tells me that my game is up to date when I know for a fact it isn't.

A couple years ago I tried updating my game without having the game running and it messed up my whole game and made me not be able to play it for months so can someone please tell me what the problem is??

Thank you so much if you help. I'm sorry if this is terribly confusing, I don't know how quite to word it.