I would sit down with your fiancée and figure out your monthly income. Make a list of essentials that you have to pay (gas, groceries, rent, cable, electricity, water, trash pick up). Find ways to lower those bills, like getting rid of cable and just having internet (Netflix can go a long way) or making meals with cheaper and generic groceries. Then make a list of things you spend money on but don't have to, like movie tickets and clothes shopping. Limit your expenses in those areas. Go on free dates (google it, there are some creative broke people out there).
Also, I personally do my grocery shopping at Wal-Mart, and then scan my receipt with their savings catcher app. It compares their prices to those from the local weekly ads, and if someone else has a better price, Wal-Mart pays you the difference. You can use the money saved any time, and it's super easy to do.