Do your other packs show up, or is this your only one?
If you go to your library on origin, choose The Sims and click extra content all your packs should be displayed below. Have you played it there before? Otherwise you might have bought/activated it on the wrong account.
If it's on the wrong account you need to contact support. The chat is not avaliable for all regions for all options, try choosing other details if you're given something else.
Maybe the site is registering that I'm in Sweden even though I chose US. Worst case you have to talk with them on the phone. Better you than me if you live in the US at least it's a language you speak daily, I only write it 😉