No, based on your height and weight, I believe that you will make a very good fit as a middle linebacker. You have the ideal size for a middle linebacker in Division 3 College Football.
My best advice for you is to work hard and perform very well in practice every day. In addition, what you need to do this (and every) offseason is eat healthy, exercise by doing weight lifting, and either jogging or going for a long run every day. If you do these things, you will get faster, stronger, and into better shape, which will greatly improve your chances of becoming a successful, top notch middle linebacker in Division 3 College Football.