Include all variable expenses now, car maintenance, electricity, heating, these can vary throughout the year you need to calculate them and come up with an average monthly amount. None essential expenses like eating out coffee at Starbucks, weekend getaways, extravagant vacations, fancy clothing, motorcycles, ATV's, if you use them, write them down, realize these are wants, not needs. Now total these all up, fixed expenses, variable expenses, and non_essential expenses,there you now have your total expenses.
Consider putting yourself back on cash. If you think you shop impulsively because it is so easy to use plastic, try to give yourself a cash allowance every week. You may go over the allowance, but you will have to go to some effort to replenish it. This can be a great way to get a handle on spending.