Chondromalacia but xrays lookfine. Why does the crepitus in my knees sound so bad still? I want a normal life without worrying my knees will get worse.

Quadriceps exercises. X-rays do not show everything, an evaluation, mri, might help clarify. Straighten your quadriceps muscles is your best therapy.
Cartilage problem. Chondromalacia literally means sick cartilage. Since cartilage doesn't show up on an x-ray, you can't see it. The grinding is from the two rough cartilage areas rubbing together and is called crepitus. Exercise and being sure to properly balance the knee should help some. A brace may also help during painful times.