Hey -
My son has/had sensory processing disorder as well. As others have said, you might want to try to restart OT during this transition/school period. My son's therapy ended when the therapist said he was "done" with therapy, but in my opinion, he still had a TON of issues that needed to be addressed. So, I enrolled him in gymnastics and dance classes. Those classes really helped him be better about addressing all of his sensory issues. However, before all of that, his therapist actually came to the school and observed him in the school environment and gave tips to the teachers on how to address a variety of issues.
I think the most important thing for you to do is to make sure that the teachers and principal are aware of the diagnosis. The reality is that your daughter is allowed, by law, to have special accommodations. I love the idea of the headphones that someone else mentioned. For us, my son was allowed to sit out of the things that were really horrible for him (my son attended a private school for pre-schook, K, and 1st grade). The Kindergarten teacher actually had a "bear cave" where the kids could go when they needed some quiet time. I think my son used it more than anyone else. By the end of 1st grade, he was really much better (in my mind, essentially cured) and so I transitioned him to public school. I never had to address anything in public school, but I did notice that the public school had a room labeled "Sensory Lab". I have NO idea what was in that room, but I have certainly heard of kids getting time out to go to sensory labs during the day - if they needed it. So, I imagine that is how this lab functioned. You need to find out what kind of accommodations your school has. And honestly, they are probably going to need paperwork verifying your daughter's diagnosis before they will implement a plan.
Oh..and one more thing..are you doing the brushing on her skin at night? That was always a HUGE help with my son. It really seemed to help ground him.
Good luck!
L.