Talk to Dermatologist on Skin

My skin was very fair as a kid but know that im 18 I became yellowish is there any none dangerous way to get my fair skin back? I have a dark area arround my mouth and I have 0 pimples or scars but my skin is just super dull dry yellow and dark! In the morning when I cleans my face with (Dior snow face wash) my skin is super pink and white but one hour later in the house not even getting myself outside my skin becomes yellow and dark again! I use Dior serum and moisturizer and also sunscreen when needed and adding up to that I always cleanse my face twice a day morning and night