Plagiarism, Second Offense

So in my first year I was in a bit of a bad mental state (not an excuse, I know) and plagairised. I was given an R/F for the course and a warning, but nothing else. Since then I have not cheated even once in my classes and have consistenly gotten A’s and B’s throught my own effort. This semester I earned all A’s except for one class, in which I had written an essay that had portions of it paraphrased but I had forgotten to site it. I was not very confident about the paper to begin with and had been given no prompt so I had to come up with my own thesis, something I’m not so great at. My teacher has failed me for the course and told me that he only requested I be given a warning and that nothing else will happen except being contacted by someone from Student Conduct. He is unaware of my prior offense. This time I really did not mean to plagiarise and there was nothing even close to copying and pasting involved. My question is what will my school do to me? I really hope for just probation and maybe a suspension of priviledges. Will they expel me?

I am a junior who is, hopefully, going on to senior year.