I just wanted to add, from what I’ve read here in the last couple of years, this job is probably not a good fit for you, but it sounds like you are a hard-working, dedicated, competent employee, with a good sense of integrity - it might not be too big a stretch to take the fact that you aren’t a good fit at this company as a compliment. Can you imagine what kind of asshole you’d have to be to fit in properly there? 
I have to agree with this. Think about it this way. If a company doesn’t value competency and professionalism or some sort of objective metric like sales generated, how are you going to be evaluated? Most likely by the arbitrary whim of your manager. And that usually means your ability to suck up, do shots at happy hour, hang out with him at strip clubs, score him drugs or whatever other douchebaggery your boss is into that makes him think he’s awesome.
If you’re refusing to play the game or your values are out of whack with your management, you’re not going to advance.
At my previous company, my primary issues were that I was hired by the wrong person and didn’t ask in advance what my promotional prospects would be before agreeing to come on. The person who hired me valued integrity and competence…a LOT. Then she left and the person who took over valued image over anything else. He was a hotshot and wanted people to stroke his ego. When he took on new hires, he groomed them - and not anyone else - for promotion. Occasionally, people who weren’t his hires were smart enough to ask in advance what their prospects were and some were even able to get a verbal semi-commitment to a promotion on entry. So they were the ones who got promoted. Not me.
Of course, that guy was eventually fired for misuse of company funds (apparently being a hotshot entailed staying at the Ritz and Four Seasons when traveling while making his underlings stay at the Holiday Inn) and for sexual harassment. Go figure.
Either way, it doesn’t sound like you’re going to get an answer or a promotion.
Also, I’d listen to those who are saying that you may also want to evaluate how you’re coming off. I obviously don’t know you, but it’s very common in general for people to have very different ideas about what is appropriate tone in the workplace. I got chewed out in the middle of a meeting last week by a co-worker. In front of my boss and four other staff members. She came over Thursday to apologize because apparently she had no idea that what she said and how she said it could possibly be considered remotely confrontational. So even if you’re not going to have a soul-searching moment, at least listen to the way other people talk and what comes out of your own mouth. How you contribute is almost as important as contributing itself.
You are going to have to be able to prove a statistic pattern of not promoting due to age to get to age discrimination. Otherwise, it will simply end with “Chimera doesn’t have what we were looking for in those positions.” Are other people of your age not promoted? Age discrimination is really hard to prove, particularly in a small company and particularly regarding promotions and job assignments.
Start looking.