It’s great that you’re interested in Psychology and writing because the two hand in hand. Although it’s different writing than an English major would require, there are plenty of writing assignments in Psychology. Most programs will offer a thesis as your capstone, and this could would a research paper of 40-100 pages in length. It’s published and kept in the school’s archives as well. In your classes and in the thesis writing process, you’ll hone your writing and research skills for sure.
That said, if you want to do a minor as well, you’re welcome to. The subject can be something you feel in conducive to your larger studies or a subject you love. You might find places where your major and minor intersect, but at the very least a minor will be classes you enjoy that also boost your overall GPA.
Good luck in your studies!