You might have bought the wrong one. But you could say the same thing had you bought the 15". There's no way to know until you've used both the same amount of time to know which one is best for you. Don't worry about it too much, I'm sure you'll thoroughly enjoy your machine (I ordered the same one, it's in transit right now). Don't regret your purchase, it's too great of a computer to do that.
Just relax, you have a beautiful machine and everything will turn out fine.
Just relax, you have a beautiful machine and everything will turn out fine.