I have been teaching parenting on and off for 20 yrs. It is horrible to see what the kids are getting their hands on today.
What I have found is that kids FIND ways around these blocks.
You are the parent...She is a kid. She should not be allowed to block u from twitter, etc. at 12. I am kinda old-fashioned, but, I have seen too, too, too many kids step on their parents at age 12... You are not her friend.
I would talk to the therapist and tell her that u are not comfortable w/ her blocking you and tell her what u would like. I am not a therapist, but, I did not allow my kids do do any of that at 11 and 12. If they chose to, my husband walked up to them and told them that they were not following the parental rules and it was taken away. Period.
Keep us posted. I am so sorry that parenting has gotten really hard for so many of us. I still keep in touch w/ a group of parents who had "challenging" children over the last 15 yrs. It HAS NOT been easy for THEM. You do have your hands full and I am glad u have sought out help. Not all kids are EASY...I know. I have worked w/ many, many families over the yrs.
All this technology is making kids grow up way too fast, teaching disrespect and teaching kids to lie. Of course, not in all case...but many !
I hope this helps.
One of the Moms I did work w/--Her daughter is 16 and was cutting. In fact, it sounds like a ditto situation. She took her daughter to therapy, too.