My daughter sees a CBT. She's worked with him on a number bullying situations. They approached the severity of what you describe, but because we identified the ring leaders of the abuse, the school was able to address. Granted, we were in an elementary school situation which made it a more controlled environment.
Document every incident. Keep a written log with times, dates, and NAMES. Use neutral language, and document as "DD reported today that...," but do not downplay the action, if a touch was unwanted, don't say "he hugged her," but "he hugged her against her wishes." Keep this document. Until you are ready to disclose the identity of the perpetrator, send a redacted copy of your entire log after each incident to the school councilor, simply adding each new report above the log of the previous.
I would most definitely discuss with the therapist the grade placement and associated academic giftedness, as this is part of understanding the child and the situation. The differences in emotional and academic maturity, the difference in stage of puberty relative to her peers, and different life experience will all play into how the therapist helps your daughter work her way through these event.
I interviewed 3 cognitive behavioral therapists. I put DD's intellectual abilities and her associated social struggles up front. I chose the therapist that could clearly distinguish social and academic needs, and could see how DD's tests scores demanded her placement. He does not have particular experience with gifted kids, though he reported that most of his clients were of "well above average intelligence." That said, he continually reports to me how he alters his approach to DD in response to her particular unique state of mind. Realize that to be a PhD psychologist, you need to pretty bright yourself. I've found that using the PhD as a starting point gets me a pretty good group of people to interview, as even if it's not part of their practice, they've likely lived it themselves (and have raised kids that are gifted or even 2e.)
Once the initial flames are extinguished with a therapist, you might want to take up the subject of why you and your daughter are unwilling to disclose the perpetrator. The school's hands are really tied without this information, particularly if there are no witnesses coming forward. You will want to explore why you are keeping it private, and how to approach the school to disclose this information. While your daughter needs to learn to deal with these situations, she also requires support in getting herself out of the already established pattern. This is a huge issue even amongst adults, and for a situation that's been persisting for a number of months, it will require 3rd party intervention.
Many hugs for you and your daughter. For all of DD's boredom in school and educational neglect from the school, it's been the bullying that has had me most seriously consider pulling her out of the school. May you get through this with peace and in one piece.
