I have a little update on this. I received a note from her on her graduation day. I had sent her a gift, so she started off thanking me, and then continued:
"I also wanted to thank you for all of the assignments in my classes you have been helping me on. I appreciate the time you put in for me. You're the best tutor I have ever had. I wish you the best. Thanks again! "
I guess teachers do get bonuses after all.