Practice. Reading will always help you (with any language), and watching movies and tv will train your ear. If a totally immersive experience is not an option, I do not think there is much more you can do. It is normal that a foreign language does not feel like your mother tongue, you will probably keep improving but there will always be some difference.

If your goal is to improve your writing too, I cannot recommend enough "The elements of style" by Strunk and White.