Is it permissible to break off an engagement due to the discovery of physical defects in the fiancée that affect speech and femininity, given that she is ideal in all other qualities, and the family does not approve of breaking off the engagement?

It is permissible to break off an engagement, even without a reason, but it is disliked to break it off without a reason. There should be no haste in breaking it off, because it is rare for all good qualities to be found in one woman. If the physical defect mentioned is tolerable, then it is better to complete the marriage. Otherwise, breaking off the engagement is easier than completing the marriage and then having a divorce occur.