Welcome to FlyerTalk, DutchMember!
Sorry to hear about your experience, and I believe the other posters have offered you good advice. If the treatment you received still bothers you this long after the flight, then something certainly was wrong and you should bring it to the attention of American's customer service department.
I would like to offer a few words of caution, though. While I see that you are trying hard to understand what could have led to the disparate treatment, you may wish to hold off on suggesting racial reasons without a firmer basis. I fly AA a lot, and there certainly have been times I have been inexplicably treated very badly as a passenger, even in First class. I smile when spoken to, say "please" and "thank you", and don't place unreasonable demands on the staff. Still, there are certain days when nothing more concrete than aura is the reason for hostile or indifferent treatment. And while I am of Latin heritage, I look about as hispanic as George Pataki -- so I doubt that's the reason in my case.
It is important to know, as others have pointed out, that American has a structured delivery method for some services. All the flights from Belize to Miami are even-numbered (AA 2172 and AA 2104 on the nonstops, plus even flight numbers on the flights from BZE to DFW with an eastbound connection). This means that service begins in the front of the cabin and moves rearward; you were apparently in the penultimate row. Often, the staff will run out of meal options by that point (it happened to me last month in the front half of First!).
Your craft was almost certainly a Boeing 737, as that's the only plane scheduled on that nonstop route. But confusing matters is the fact that the mileage earned between BZE and MIA is 767 exactly. Seats on the 737 are configured 2-2 in Business Class. There is no First Class.
When writing to AA, clearly itemize what services disappointed you, contrasting what your expectations were. A minor point, but one you may not be aware of as a new member here, is that it is not customary to refer to Business Class as "B". The confusion stems from the fact that there is a common Economy fare basis (booking class) known as "B", and it is differentiated by the airline as a full fare versus a discount or deep-discount fare.
You will sometimes see FlyerTalkers posting that they flew on a "B" fare -- this means that they bought an Economy class ticket. American's booking class for Business class between BZE and MIA is "J". It is perfectly acceptable to say you flew BZE-MIA in J -- we use that shorthand here all the time.
So, for purposes of clarity when writing to the airline, it will help you to spell out that you flew this route in Business Class. Follow that by explaining the great discomfort you felt by having your needs ignored by the staff, including being the only passengers in the Business cabin to not to have your dinner trays cleared long after the others had been. It would be particularly helpful if you could cite instances where your specific requests went unaddressed, keeping in mind that service can be a little tight on such a short (under 2 hours) flight.
Sorry this happened to you, and I hope that your future trips on American are more pleasant.