I'm sorry if this is not the right place to ask this question but...
I cannot concentrate on study on LSAT these days thinking about a grade I got.
I did all my best and spent the most time in this class, but the professor gave me a grade which I think I do not deserve...
I believe I did more work than any other students in the class, and whenever I asked about how I was doing in the class, the professor just told me I'm fine etc etc and did not really gave me any advice and when I asked about the grade I got she says that grade and this grade do not have a big difference etc etc...and she never ever graded on our paper or presentation so we had no idea how we were doing in the class.
How can I talk with her about changing the grade if it is possible?
I just cannot accept this nor understand it...I asked about it through email(because she is on vacation), but she said she does not have intention to change the grade.
But when I asked at least I want an explanation, she did not give me anything.
I am going to meet her this semester and hopefully I can talk with her about changing the grade but...how should I talk with her? Do you have any advice?

This is my first time to do this thing so not sure...and since I already kind of explained a lot by email, I'm afraid she feels annoying.
This class was not a required one, so now I regret taking it a lot...if I had not taken it I could have taken a different class (which I was more interested in actually...) and I could have studied for LSAT maybe.
I know it is nonsense to think about those stuff but even I try not to think about it, I cannot help&cannot focus on studying...
When you have something in your head that you do not want to think about it, how do you deal with it?
Thank you,