Is it obligatory to inform a suitor about incomplete breast development, and the resulting potential inability to breastfeed? And when should this be done?

The majority of jurists hold that the defects which must be disclosed during engagement and which permit annulment are those that prevent sexual intercourse or are contagious and repulsive diseases. Therefore, you are not obligated to inform the suitor about this defect, especially since its removal is possible and easy. You should strive to do so.