I agree with the previous advice.
First, absolutely get rid of the car, this is where most of the possible savings are. You said that you are upside-down on the car loan. Would you be willing to give us numbers on that and more details on the loan? When you sell the car, could you use the money to pay off the loan early?
Second, I might move to a 2-bedroom place if I were in your situation since I would consider the car loan Hair-On-Fire-Debt. However, it depends -- if selling the car already eliminates most of the debt and gives you a substantial savings rate even while still living in your current place, that place would still be a bit of a luxury, but possibly an affordable one. It is impossible to judge this without knowing numbers.
Btw., are the numbers you gave actually in $ or in €?