Please recommend a daily whitening product for everyday use.

As I get older, my skin tone feels dull and patchy. My husband even teases me, saying it looks gray. I look sickly, and blemishes are noticeable.

I am currently using the Niacinamide serum for whitening care, but even though this is my third bottle, I still feel like I'm not sure if I'm using the right product. I feel like my skin has brightened up a little, but I'm not really sure; ^^ On the other hand, it seems to have smoothed out my skin texture well.

I am frequently reapplying a sun stick, and I am not wearing any makeup other than lip makeup.

Please recommend some products that would be good to add to my daily routine.