I've had this problem in the past as well. Regarding the "is it me?" question, I don't think there's anywhere near enough info to answer, but the fact that you're being introspective on the matter is a very good sign.
I can offer a few pieces of advice. First, be direct but exceedingly rational with your co-workers - especially your superiors. Sometimes it helps to start conversations regarding conflicting ideas under the assumption that you're wrong.
Also, watch your assumptions. Sometimes when people get frustrated about things it's really easy for our assumptions to solidify into fact, and it's just as easy to feel justified launching into a spirited argument fuelled by all this fact.
Finally, if you think you're expressing yourself well, and you don't agree with the direction things are taking, you're 100% totally justified in leaving. I don't care if you're a minimum wage employee, your time is your scarcest resource. Don't invest it in something you don't want to own.
Annnd really long (but hopefully interesting) anecdote time...
I used to work for a very small, now fairly famous start-up non-profit which was cofounded by Edie Widder of Discovery Channel/Giant Squid fame. She wasn't running it because she didn't feel that she had the fundraising or business acumen. She decided to cofound with a former marketing exec, and to make him CEO.
I worked for them indirectly and directly for a combined 5 years. It was the kind of life-consuming work that one only does when they're very passionate. And I was as it was incredibly rewarding.
Our mission was to develop very inexpensive sensors for very broad scale in-situ monitoring of estuarine environments (the mission has broadened since then). When I first came on directly, we made a huge push to win a seven figure grant. Engineering was told by the CEO to push, and to push hard because this would be the money we'd be using to go from prototype to small-scale manufacturing.
Except after we won it, engineering wasn't given a budget. As time went on, our feeling was that we were having to beg for every expenditure. In the mean time lots of money was being spent on marketing, with the justification that it would be bringing in the "real big bucks." Of course, there was also plenty of disagreement over certain expenditures. Was X really marketing-related, or was that a personal expense?
Obviously there was lots of infighting -- mostly by people who typically like to avoid confrontation. People would wait to address something until they were so exasperated that it'd just boil out, and everybody involved would get very defensive very quickly.
I started to wake up to the idea that we were working more on our arguments and less on our mission. I'd spent every second I could over the past five years building a monolithic realtime telemetry system with the idea in mind that this was a step toward literally saving the world. Leaving felt wrong, like I was abandoning my purpose and my friends, but after a while staying felt more wrong.
On my last day there I sat down with Edie for an informal exit interview. For the first time I explained to her my position as directly and rationally as I could. This wasn't out of some new-found maturity, but because I had nothing to lose and nothing to gain.
I stated my observations, listened to her responses, and conceded on the points where my knowledge of the situation was lacking. At the end of the conversation I still felt justified for leaving, but I think she understood my justification. Prior to that, we were always putting her in a situation where she had no other choice but to feel cornered and defensive.
Not long after I left the CEO became the former CEO. For a brief period during this process, there were two separate sets of legal council arguing against each other - I believe with each claiming to represent the company. When the dust settled, relationships were tarnished, names had been dragged through the mud, and most importantly the work had all but stopped.
Fast-forward to today and things are much different. In many ways they've been terribly stunted, but there's better accounting, better employee representation on the board, and most importantly - a unified focus. They have turned into the organization I wanted to be working for back when I left. In the mean time, I've been in a constant struggle to find something anywhere near as rewarding. If I could afford to do so, I'd go back to work for them in a second -- on my own dime.
You'll notice that I spend a lot of time talking about the "evil" CEO here. That's not the point. The point is that a significant part of it was me. Sure, the company had some growing up to do, but I had just as much, if not more.
Although, if anyone reading this happens to be looking to make a very high-impact donation to a great nonprofit - give Edie a call. I promise she won't disappoint.