I am quite sure that it's the size from the original game. But I like that they did this; I had trouble deciding whether or not to trash my snowman room, only to remodel it into a basic foyer. I found the Wild World mansion to be nice, but quite imposing.
No rush to worry - in this game you can purchase a well for your town, a bridge, and either a windmill or a lighthouse. There is much more for which you can use your money - don't worry. You are far from completing everything.