I've quit a few jobs. In my experience, when you're thinking about quitting and asking other people if you should quit, then it's time to quit. I have tried to stick it out before and I wish I had just quit instead of trying to work through it.
How have things turned out for me?
My last employment gig that I quit was about a year ago now. I quit, then worked for a month full-time on one side project. Then a company I previously worked for needed someone for a few months, so I went back to them at 50% more pay since it was contract.
Then I took another month off to complete another side project. These projects didn't make money so I started looking for some remote, contract work. I found one pretty quickly that was using Zend Framework, which I had experience in due to using it on one the above-mentioned projects. I accepted this, at an increased rate of pay from my previous contract.
Now, that contract is almost up so I'm looking to take time off to work on another idea but am also applying to some contract gigs that interest me. I've sent off three applications so far, and I've had three interviews (the third coming up on Monday). Also, the place I previously worked at/contracted needs someone again for a few months so I have an offer in my back pocket.
As a capable programmer who can take the initiative to build your own stuff, it is incredibly easy to find work. Quitting your first job is the toughest though. But then afterwards, you wonder 'Why was that so difficult?'
This will be a great opportunity to learn more about yourself. If you quit and take time to work on your own stuff, you will learn a TON about your work habits, how productive you are, your focus levels and whether the entrepreneurship route is for you. This is incredibly valuable information to learn about yourself in your 20s. You may find after a few months, that you prefer the structure of the corporate world. Maybe it's tough for you to understand that now, but I can definitely understand why some people would prefer this.
And, if you take time off, build some stuff on your own, and highlight that in your cover letter and resume, it will be very, very easy to find work should you wish to return.
Have fun!