Did you get the water issue sorted out? You MUST have a leak unless you are irrigating a HUGE lawn. Maybe we just have cheap water or something (it would be the only cheap thing here) but I don't think I've ever had a water bill more than $35 and that's with watering the heck out of my garden (no rain in the summer) and not being very careful about showers.
If you suspect the toilet, do you mean it is always running? Have you tried fixing it? Of course, that might take parts, but it might just be that the flapper is stuck on something. In our house, we call this 'the flapperdoodle'. If you can't fix it yet, how about shutting the water off when you are not actually using that is, flushing, it? There should be a stopcock valve next to the toilet. Failing that, I guess there will be one for the whole house, though that's a little dramatic.
If you can't afford hot water, tell her you had to have cold showers because she gets you all hot and bothered
For electric, be sure the fridge is sealing well and that the coils are clean. Hang clothes to dry them.
Try dates at home. Can't cook? Well, this is a great time to learn and I'm sure Girlfriend would appreciate it. Anyone who can read can learn to cook. Get a book from the library maybe. Maybe you could get GF to come over and teach you, assuming she knows. Hey, maybe even she will spring for ingredients if you cook. Tell her you want to make a special evening, but you need to save money so you can turn things around.
-TinyFish