@MeganFord1213 The last pack for the Sims 3 was released in 2013, and the last real game update in January 2014. The game has been out of development since then, with no fixes offered for any of the issues that have arisen in the last five years. The game never ran particularly well in mac OS for reasons I don't have to get into, but it's been harder and harder to get it up and running in the last few years.
The install issues you're having—packs not showing as installed, files not being copied to their proper destination—first showed up with El Capitan, the mac operating system released in fall 2015. Since there was no one at EA to fix the problem, players were left to their own devices. You'll notice that I've been linking you guides from one particular site; Bluebellflora's work is the only reason anyone can play the game on newer macs at all.
Aside from the install issues, there's also the fact that no graphics cards released after 2013 are even in the game's database. This is mostly fine in Windows, as the game will run on an unrecognized card with only a minimal decrease in graphics quality. But in mac OS, all newer Nvidia cards and integrated Intel chips need require extra steps to force recognition, or the game won't run at all. Your computer is older, and its graphics chip is in fact supported, so you don't have this issue, at least.
You don't need to have Origin running to play the Sims 3 on a mac. You can launch it directly by double-clicking on the icon for your newest pack, which is Into the Future. Either you'll get an unknown error, or the launcher will appear. If the launcher opens, just press play.
If certain packs are installed but you haven't done the workarounds properly, the game won't launch. It's an all or nothing proposition. So you can be sure that the installed packs are behaving if your game launches. As for the packs that didn't install at all, you've already seen that they're not present in AddOns. The other way to check is to load a save (it can be a new one) and go to Buy mode. There, you can sort items by expansion pack, so you can count the icons for each pack and make sure they're all there.
As for your location, where are you trying to set it to U.S.? I don't remember having to do that for the game itself, but perhaps you're doing something else?