I'm getting along in (coder) years, and I'll just throw this bit of advice and then yell at you to get off my lawn.
I've cycled through "this isn't my passion" about 5 times in 15 years. And what I'm learning, very late, is that it can take about that long to understand the true nature of "passion," and years to develop enough facility, experience and comfort with a particular skill or vocation before you actually understand what it means to be truly at home in something that has become a part of you, probably through years of cycling through thoughts of "this isn't my passion."
"Passion," or the lack of, can be many things. It can be a deep-down intuitive feeling that you simply Don't Want To Do This Anymore. It's OK to feel that in your early 20s, or 5 months into your first gig. But, my 2c, don't give too much credence to it. Real passion happens most often with things that have beaten you down 4 or 5 times and finally have been overcome 'cause you kicked back. "Passion" happens most deeply with something that you love like a hometown, warts and all. Where people know you when you walk across the square, know which parts to avoid, and who has the best coffee. Programming, and really any vocation you chose is like a city. It's many things to many people, and rewards best those who practice a discipline of place.
So, I'd say, hold those things in tension: your gut feeling that this may not be for you, over and against the possibility that any new vocation you pursue will present the same roller-coaster of emotion: feelings of incompetence and boredom and futility, followed on by euphoric feelings of revelation, victory and at-homeness.
The trick is knowing whether you're just on the front end of that cycle, and when your gut is really telling you this isn't for you. For that -- talk to friends and coworkers. A lot, over long periods of time. But don't just go with a gut feeling.