I installed "SIMS 3 Fast Lane Stuff", "Ambitions" and "World Adventures". Then I went to the launcher, clicked the play button (I had the original SIMS 3 disc in my Laptop) and it asked for the "Fast Lane" game disc instead. I put it in, and it loaded "The SIMS 3 Fast Lane". This doesn't have my saved game, which I was playing with the original SIMS 3 disc. Has something gone wrong? Do I just not understand the expansion packs? How do I get my game back?

Thanks for your help! :-)

Sims EPs aren't like EPs in other games - you can't play either an EP or the basegame, you play the basegame + all EPs at the same time.

Your save games and CC shouldn't be affected by installing EPs, and they should work fine in later EPs (excluding CC which may need updating) - are the save game's files still present in Documents/Electronic Arts/The Sims 3/Saves (the Mac location is slightly different but I believe you should be able to translate fairly easily)?

Hi thanks for your response! I went to Electronic Arts/ The Sims 3 and it doesn't have a "Saves" file. It has "Caches", "Game", "GameData", "Support", "Thumbnails". What should I do? Does this mean the game is lost?

That is the Application path.
You need to look at the Documents path for the User folders and Saves.