I pretty much agree with Shawn, who seems to have the consensus opinion.
My friends complain to me about not getting stripes all the time. I honestly don't care that much about rank advancement, and my tolerance for people who complain about it is pretty low is a result.
For me, if you work hard, if you really master the skills, and you compete and win on a regular basis, you can establish yourself in the gym in such a way that, regardless of how big the gym is, the work will be noticed.
I don't know what your instructor's criteria is for promotion, but if you work your ass off in the gym, chances are you'll run into it eventually. Until then, focus on the skills. Those are more important anyway.
I'm pretty much the same way. I don't focus on when that next stripe is going to come or how long it's taking me. If you do that you're going to drive yourself crazy worrying about your rank rather than how good you actually are.
I have also came across people that complain about not getting their first stripes or second, third, fourth, or even their blue. That's why I say ask your instructor where you need to improve, don't complain about not having the stripe. Honestly I would hold someone back who's complaining because in my opinion if you are complaining about belt rank then you aren't ready to be promoted.