Budget, budget, budget. It can be done. We lived off that much. This is what we did.
*We signed up for quicken.com so we could see how much we are spending where and it was automatically updated by our bank (it costs $3 a month) so we could realistically budget for things. I always look at this and also our bank account online before going shopping so I have a idea of how much to spend on groceries. It also made it easier to say no to the things we really didn't need.
*kept meals simple (great meal ideas on Kraftfoods.com) and made double of things to freeze for fast meals.
*to save on gas, we would plan outings beforehand to make the most of it...example: We'll leave home early so we can get the things we need at Home Depot on the way to Krista's birthday party. On the way back we can pick up the dry cleaning too.
*We saved a bunch on entertainment by doing a lot of the activities, renting movies, and books from the Local Library. They usually have story times for kids, family movie nights, and other things like fairy tea parties, etc.
Hope this helps. It's hard at the beginning to learn how to budget, but it becomes second nature after a while and then you start getting so good at it that you are able to save money for all the big things. It's a wonderful thing staying home with your kids, you get to see so many adorable little events happen. Good luck!