Dreaming about aggressive dogs can symbolize feelings of fear, anxiety, or a sense of threat in your waking life. Dogs often represent loyalty and protection, so an aggressive dog might indicate a situation where you feel betrayed or unable to trust someone close to you. The fact that the dog almost bit your sister may suggest that you are worried about the safety of loved ones or that you feel a protective instinct over them.
Being in the bathroom during the dream could represent a desire for privacy or a need to process your emotions. Bathrooms can symbolize a place for cleansing and reflection. This setting might indicate that you are dealing with some personal issues or feelings that you need to confront.
Consider reflecting on any current situations or relationships that might be causing you stress or anxiety. It may be helpful to communicate your feelings with those close to you or seek ways to address any underlying issues in your life.