Hi, thanks for your query I understand your anxiety as your engagement is nearer. I shall try to help you about your concerns one by one You have not mentioned your age and gender. Dark circles may be due to inadequate sleep, fatigue, iron deficiency, lack of balanced diet, physical or mental stress, hereditary factors. Addressing the underlying cause will help in treatment of dark circles. You may apply retinol based cream at night by prescription of a dermatologist . Other options include glycolic peels, laser , mesotherapy. Complexion cannot be changed drastically but you may get rid of superficial tan and get a healthy glowing skin by skin lightening peels from a dermatologist. Use a broad spectrum sunscreen during the day. For post acne dark spots you may use hydroquinone , tretinoin and a steroid based cream by prescription. I suggest you to take treatment by a dermatologist as your engagement is nearing and best possible treatment of these may be started for you according to your skin type. Hope this helps you . All the best