Hi,
When you say over-responsive, you mean she's sensory avoidant, right? The strategies for this would be different to a sensory seeking child who would more likely benefit from weighted therapy, heavy work etc. Look at the environment from a sensory overload perspective, including the reading material itself. Does she hate the feel or sound of paper being touched, pages being turned, book being moved, or rubbed against the table? Is there too much distraction? aural, visual, etc? Is the light right, is the chair comfortable? Does she have other vestibular issues, like poor balance, fear of heights, or low tone (floppy)? Would a bean bag or hammock chair be better than sitting at the table? Does she have any other developmental issues? As mentioned above, does she have any visual processing difficulties?

Routine and structure are good to have in place too, visual schedules are great - have some relax time between school and homework time if possible. Move to a quiet space, no music, no other distractions, even cars going past can be too distracting for sensory over-responsive kids.

You say she's just started school, I'm not sure where you are, but does this mean she's 4 turning 5, as it would be in Kindergarten here? or is she Grade 1 (6 turning 7)? Can she do other activities where she is "crossing the midline", using the right hand on the left side and vice-versa? Search for 'crossing the midline OT' if you're not sure what I mean by this.

Bernadette.