Okay, so what you really need is to start dealing with the problems you have, which are leading you to overspend, rather than find a way to earn money. Believe me, been there, done that - unless you get your spending under control, it will always expand to eat up every bit of your available money (and then some). The best way to save money is to not spend it.
So, it sounds like you're very down (possibly depressed) about your job. You will know yourself how bad that is, but if you think you need it or would benefit from it, please consider getting some counselling. Yes, you will probably have to pay for this yourself and it's not cheap but it is possible. And getting help, knowing you have to put money away for that and therefore cannot spend on other things, might be enough to kick-start you into changing things.
Otherwise, you need to start doing all the things that it sounds like you already know you should be doing. Namely, never buying food at work/in town and only eating what you have prepared at home and brought in with you. Do you have access to a microwave in work? If not, invest in a good, wide-neck flask. It's coming into colder weather now so it's soups and stews all the way. Cheap and easy to prepare and you can cook once at the weekend and have enough for the week (albeit a bit boring to have the same thing every day). Or, if you have a decent sized freezer, invite a good friend over to help you and spend a day cooking enough for lunches for a month. If you can't face going to the supermarket, order online (less chance of impulse buying anyway). I nearly fell over when I saw I'd have to pay 40 euro for a non-glass wide-neck flask (to replace the Thermos one that I broke the second time I used it) but then realised that even if I just used it every day for one week, I would have already saved as much as I had spent on it.
And figure out how to de-stress a bit at least. Where do you live in comparison to where you work? Can you walk or cycle part or all of the way? It's amazing how pounding your frustrations out on the pavement can make you feel more positive by the time you get home.
How is your budget structured? Do you have a proper one of the kind that involves micro-managing to a certain extent? By that I mean, x amount for food, x for drink, x for magazines, x for snacks etc.
Honestly, you sound a bit like how I was (and sometimes still get - depression is a very difficult thing to beat) so feel free to look back through some of my posts to see how things can go if you don't start figuring this out.