Is It Too Late to Change Career Path to Become A Doctor?

I'm 22 and I'm currently finishing my last semester at college that will give me a BA in psychology. Right now I feel like I'm at a crossroad. I love psychology, but I don't know if I would be happy continuing on to graduate school in that area. I feel that I have always been interested in becoming a doctor. I wanted to be a doctor as a kid, but never felt that I was good enough. I have always had a strong interest in health. Even in psychology, I was drawn to the health aspects such as occupational health psychology and health psychology. These thoughts have been raging in my head for quite some time. I know if I change now, it will be a lot of work ahead, but I feel that I can take it, and what I learned in psychology can be carried over to medical school. Any thoughts on how I should proceed? I feel like staying at my university for a bit longer and adding a minor in biology, or can prerequisites be done at a community college? Any help and suggestions will help me out a lot.