My gf and I eat on about $100-$150 per month, which we accomplish by buying the absolute cheapest stuff (68 cent cans, etc) from Wal-Mart, getting bulk meats ($10 for a shitload of chicken, yes please), etc., and buying veggies. From there we just cook whatever. Something that helps a lot in terms of efficiency for food is a site we use called supercook.com. You put in all your ingredients in your kitchen and it tells you what you can make with those things. This way when you're sitting there with a carrot, one pork chop, a packet of ketchup, a can of peaches, and a chocolate bar, it'll tell you what amazing dish you can make with it. This makes your ingredients go as far as they can, instead of sitting there for a long time.
Plus, cooking for yourself is fun (at least for me, I LOVE cookinng) and it seems to be healthier-- I've lost a lot of weight just cooking for myself-- granted, not eating that second helping because you want the food to last longer helps too.
Some cheap and high-yield (long-lasting) foods we make are:
- Red Beans and Rice : Rice, Kidney Beans, a Sausage, and Salt : This tastes great (though not high end by any means), is super cheap, and gives a lot of servings. (You're looking at about $4-5 [Bag of rice, 2 cans of beans, 1 sausage] for about 6 servings.]
- Tacos : 2 tubes of ground beef, some seasoning, plus tortillas, refried beans, lettuce, cheese, tomatoes, salsa : This is more of a "luxury meal" as it costs more, but you can get all that for about $20 at Wal-Mart, and it'll make a buttload of tacos, around 10-12. More if you buy more meat, as the other stuff lasts a long time.
- Pasta : Pasta will make you fat, but it hands down is the cheapest-for-amount food out there. I made some delicious-ass spaghetti for $1.75 that lasted about 6 servings. Any pasta is really easy to make, especially if you look for recipes or use supercook. Again, it's not super-healthy, but if you need to crunch your food money, it's the way to go.
- Soup/Stew/Curry : The leftovers meal. Basically, look up a recipe for soup/stew/curry with whatever vegetables and meat you have left over, and make it. The type of curry we made is SO DELICIOUS. We've eaten about 6 bowls worth and I'd say there's enough for 10 more. This can be pricy if you buy stuff specifically for it, but again, this is kind of your leftover ingredients meal.
There are some other ideas, but if you go for "filling" foods you can eat roughly the same for less money.
And as always, look for the 60-70 cent cans at wal-mart. It's not that shitty, and they work great as sides or ingredients. One can used purely as a side will last you about 3 servings, so that like 20 cents a serving.
I know it's hard to change how you eat, but you could potentially drop your grocery bill by $50-$70.
Also, $500 discretionary seems high. I know you said a good bit of it is for bills, but BEYOND bills I would set discretionary at no higher than $100. That's $25 of entertainment per week, and that's easy to do. That's a movie a week (hint: save money and don't go to movies. Download older movies or get Netflix.) If you buy a new game, congrats, you've only got $40 more for the month. To me, $100 "misc." money per month is easily enough. I would put your WoW money into this, btw. Quite frankly, WoW should eat up so much time that you shouldn't even have to worry about other random expenses.
No impulse purchases. Maybe I just have insane self-restraint, but I see people buying things they TELL ME they don't need. I rarely buy anything for myself, and if anything, I make a grocery purchase as an impulse buy.
Don't buy convenience items, like $1.50 bottled sodas. Restrain yourself and just get the off-brand 2 liter for 80 cents. The best way to restrain yourself is to think about how outrageous the price is for a cold drink. Is it convenient? Hell yes. Is it worth it? Hell no. I decided to buy convenience drinks as little as possble about 6 months ago, and since then I've bought 2, and was mad at myself for one of them.
The number one problem I have with money is my GF, and that's because I hate to say no to her. I feel she deserves nice things sometimes, so most of my unnecessary expenses go towards her.
All the above being said, I've saved up $3,000 in about 5 months from a minimum wage job. Do I have as mch debt as you? No. I doubt I have as many bills as you. So I can't be a great comparison-- BUT! You both are bringing in money (My GF brings in just barely enough to pay her bills) so you should be able to save up your $7k within a few months, I believe.
I hope this has been in the slightest bit helpful.