A friend here asked me in a personal text how a guy like me who is a non-smoker and somewhat fit got the booster while he's not been able to. I REALLY understand the frustration and since it may help more than him . . .
My daughter has such immune deficiencies that her doctor wanted her to get her shot (not booster) across from an ER because there was such a chance she would crash. She also had to load up on antihistamines first. Where we went is not a popular place and being fairly early, we were pretty much alone with the nurses giving the shots toward the start of their day. I was talking to one as the others were processing my daughter and we were having just a pleasant conversation when the nurse asked what I do and when did I get the original shot. Seeing the opportunity, I related - honestly - that since retiring from the Gummint I teach firefighters (teachers move to the front of the list here), got the 1st shot exactly 6 months ago in March (that's a criteria), and that in a couple of weeks I would need to fly far away to be the oldest person (65+ group) stuck on a work boat for two weeks with 28 other people, a few of whom are anti-vaxers from the Texas oil patch. (need their job skills so unavoidable) It was living on the boat with so many people that really had me nervous and asking for a booster in the first place.
The nurse then asked about me having immune deficiencies and other conditions. By this time my daughter had her shot and is standing with us. I mentioned taking blood pressure pills and to be honest, the nurse was kind of prompting me to think of something more as an excuse. That's when my brilliant microbiologist daughter pointed out that I occasionally have itchy dry psoriasis. What she knew and I didn't is that it's an auto-immune condition that so many people have which nobody recognizes and doctors don't record it unless it's really bad. That was all it took to push my case over the edge.
So what made the difference and how much can you use? I don't know but in retrospect, it was also in part being friendly and in the right place at the right time.
ref for more about auto-immune conditions:
https://www.goodrx.com/blog/what-does-it-mean-to-be-immunocompromised-coronavirus-covid-19/