This dream may symbolize feelings of being overwhelmed and out of control in your waking life. The act of packing up and leaving a place may represent a desire for change or a need to let go of certain aspects of your life. Your little sister picking you up could symbolize a sense of dependence or reliance on others. Forgetting things and turning back to retrieve them may suggest a fear of missing out or not being fully prepared for a new chapter in your life. Your girlfriend taking the wheel and becoming unconscious could represent a feeling of being unsupported or burdened by a romantic relationship. The car losing control and going into water may symbolize a loss of direction and being overwhelmed by emotions. The act of trying to wake your girlfriend and realizing it is a dream may suggest a need to take control of your own life and emotions. Overall, this dream may be a reflection of your subconscious fears and anxieties about change and losing control in your waking life.