Hmm I'm not entirely sure what your question is. But if I'm guessing correctly, I don't think your answer is wrong. Both 'personal' and 'reflective' tone would be right in the context you gave. 'Personal' because it's an intimate reflection, and 'reflective' because she's considering a possibility of where she was at fault. You could even describe the tone as perhaps 'tentative' or even 'considered' (of course within reason). But from what I see, 'personal' and 'reflective' pretty much describes the same thing. There are lots of ways in which you could describe tones. In other words, there is no 'one-right answer'. It just has to hit the same ballpark, and I think your answer is reasonable. I don't know how they mark the exams over in Korean SL, but I don't think there should be any qualms with what you wrote.
Hope that clears your question.