Bro chootchiew, your problem is the next job, not this job. You options seem to between giving up your current job and losing $2,750 per month versus being unemployed.
Would your self-esteem be better off with that latter option ?
Is it the nature of your current job that makes you feel worthless ? Or the salary ? What if your current job pays you $8,000 a month for doing exactly the same thing ?
Since you have made it clear that you are not businessman material, I will not advise you to pursue in that direction. You either have the courage to brave the storm of uncertainty or if circumstances dictate that you start your own business. So essentially, with your choices being narrowed down, your problem is really about the next job, and the next job does not seem to be on the horizon.
Perhaps you should start looking out for the next job. If you quit your current job and remain unemployed, my fear is you may lose your g/f too. Your self-worth is going to take a bigger and harder knock.
Focus on your next job, bro.