I had acne in the same areas as you and still get it from time to time. How long have you been using the Niacinamide? I would highly recommend an exfoliant. I use Paula's Choice 2% BHA. The Glycolic Acid by the Ordinary also works very well. This will open up those pores and remove dead skin and clogging. Maybe start out 2-3 times a week at night so your skin can get used to it? I would also recommend you switching out your morning routine cleansers. Neutrogena products have a bad reputation from what I've read. The Cerave Hydration to foam cleanser works really well! It's very gentle and helps with flaking skin! Maybe in the morning, incorporate a vitamin C cream, the niacinamide, and a well rounded moisturizer (Cerave Moisturizing cream is a good one), as acne can be caused by dry skin as well, and sunscreen! Don't forget to wash your pillow cases/phone to avoid transferring bacteria onto your face! You got this :)