Unfortunately, you can not rely, at all, on BA loading your special meals.
My wife has an allergy to MSG (monosodium glutamate) and requests low sodium meals, because, according to BA definitions of special meals, this meal contains no MSG.

BA has failed to load her meal many times, for example, in First Class long haul from Dallas, and also failed to load the meal on Concorde from JFK (a few years back of course). The flight crew always does their best to figure out something, but it is reprehensible and pathetic that they fail so often, even on Premium tix.

Moral to the story: Plan to bring any special meals yourself. Order the special meal but do not rely on it. You can always supplement your foods with salad, fruit, etc according to your restrictions.