Sounds like you really try to save. I agree with Pat about paying yourself first (savings first). Since your check goes to discretionary items (well, groceries and gas are needed), those areas may be the best areas to try and find savings, especially in entertainment. Since I don't know the size of your family, you may have a large grocery budget.
For our family of 4 this is our monthly budget (and i drive to and from work, 3 miles each way):
Groceries: $400
Supplies: $50
Clothing,etc: $100
Gas: $300 to $400
Entertainment: $50 to $100
I had to build in a cushion for gas as prices keep going up and entertainment as we do more in the summer (golf, pool passes, day camps, etc).
But DH and I put away $300 a month (auto deduct from paycheck) for savings. It's nice to have a little savings built up for emergencies.