IPhone data running out & a little over a week left on the billing cycle

I got a message from AT&T today saying that my data usage was at 65% for the current billing cycle and this billing cycle ends on October 15th. That's next Tuesday (which I know because I'm a hardcore Walking Dead fan and the fourth season starts back in a week). I NEED my phone because it is the only communication device I have. We have no home phone. My mom pays the bill and she doesn't want to pay the extra $10 per GB if I go over. I help out at my mamaw's and they have no Internet. Everywhere I go, there's always a locked Wi-Fi access point.

HOW CAN I STOP USING So MUCH DATA! I have had my iPhone since last December and I've never had this notification before! And I have gone to hospitals, bookstores, tattoo studios and even out of state and have never gotten this notification before!

This used to happen to me all the time! Just make sure that anytime you have the chance to be connected to Wi-Fi that you are connected to it! And make sure when you are done with an application, that you completely exit out of the app. If you are not familiar with this, double click the home button and hold down on an app and press the x. This will not make you lose anything. It just saves battery and data! And don't use it unless you absolutely have to!