Is it ok to get a breast reduction from a 32 b cup to a 32 aa cup?

I doubt it: It seems like what you are asking for is a simple mastectomy, which is very rarely done for cosmetic reasons. Also, cup sizes are non-reproducible, so we never guarantee a specific cup size after reduction or augmentation. Why would you want to reduce a "normal" sized breast to something almost non-existent?

Not likely: Most insurances will expect to have at least 500 grams of tissue removed on each side, in order to qualify for a breast reduction. It is unlikely that you would meet this requirement.

Yes, but...: Good advice would necessitate in person consultation with well experienced board-certified plastic surgeons. The main question i think most plastic surgeons would ask you would be regarding your motivation. You will need to consider the downsides of breast reduction surgery, including scarring. Sometimes, some degree of reduction can be achieved with liposuction surgery. Best wishes.