Google sexual materials.

I feel like I've lost control.
My daughter is almost 12 years old.
She was grounded from all electronics should brought home per computer from school.
When she was told not to.
She googled on the computer from school sexual.
Topics. The IT department has them blocked. But they still could see what sights she tried to Google.. So I wanted to know what sites she was on so I asked the principal I have not got any answer yet. My daughter is very impulsive and I think she has ADHD she doesn't have a appointment with the neurologist until December. She also refuses to talk about this. Help what should be my next step?