Help with the SIMS 3/SIMS 3 PETS EXTENSION

Hello,

I downloaded the Sims Pet Extension last night on my MAC computer, without knowing you needed a base game(whoops). It installed fine, but it said I needed to get the Sims 3 Installed first. Both of my purchases were downloadable (NOT PHYSCIAL). I purchased the Sims 3 online today, again the downloadable version, and I started installing via Origin. Both of my games are on Origin, still with the options to "Install" them. As the Sims 3 was installing, I checked to see where my Sims Pets extention was. It was no where to be found on my computer. I checked downloads, trash can, applications...etc. Text Edit still has info documents of the game like I still had it on my computer. When I tried re-installing Sims Pets Extension, it wouldn't let me, saying that Origin was already opened on another computer (there was no other one). It said on the Origin application it was installing, but the "Install Sims Pets Extension" application wouldn't let me do anything. As the Sims 3 was installing, it kept freezing in the middle of the installation, so I had to restart my computer to restart the installation. Everytime I tried reinstalling the SIms 3, it would freeze and I would have to restart the same process. Can someone please help me solve the problem? 

Thanks