Don't try to keep your feet planted. That will stop you from getting to weight transfer and fluid motion needed for a good, spinful serve. I assume you are using a platform stance keeping your back leg back through motion. Toss the ball a little, little more out in front and by the time you start to swing to make contact with the ball, all of your weight should be on your front foot. This also requires a healthy knee bend.
Fear is a waste of time, and pain breeds fear -- ignore pain and live life.
Wilson ProStaff 85, Iso-Speed Control crossed w/anything cheap @ 60lbs.