I will start by stating I am a teacher. I am always skeptical when the kids come to me with complaints of other teachers who "hate" them. This is not because I believe it to be impossible, but it is usually extremely rare and the product of a totally different problem.
If you have evidence that she is grading you differently, I would present it to her, and if she refuses to address the grading and change the grades, then present it to an Administrator or Head Teacher. Keep copies. If she's a new teacher, it could easily be that she's simply really bad at grading on a rubric and while that's not fair to you, she may be more willing to fix it than you'd think.
However, since you have spoken with her and come away confused, I'm thinking that it's not a cut-and-dried case of "She graded me wrong" so much as it's you don't know what she's expecting. She may not be very clear in what she's expecting, to be fair! (New teacher and all.) But that doesn't mean she's necessarily grading you unfairly because of some personal grudge.
Was your friend's paper very similar to yours? Did you illustrate the theme in the same way? Were they of equal quality? There are a lot of reasons one person gets one grade and another gets a different grade. Generally, the teacher should be able to explain those, but if you're walking away without having the discrepancy answered, that's not a great idea either.
Another thing: this is not new. Her not letting me do something that she let other students do. Last semester she let two of her other students pick a project that she did not let me when I asked her. When I confronted her, she did not have any answers. She even looked embarrassed that I found out. Instead, she just asked, "What do you want to do then?" I could not believe it.
Granted, I'd have a way better answer than this, but I totally restrict student's selections based upon various factors. If I know in Pd. 3 Advanced, one student has selected a topic and their best friend in Pd. 6 Regular who routinely tries to get the other friend to do her work tries to pick the same topic, I will decline their choice. I will flat-out tell the student that the topic was already taken by others, even if not in this class, and I don't feel it is appropriate. But I've declined for so many reasons, I can't even count now. That's what happens on projects where topics must be approved and why I request topic approval on those.
I have one student this year who insists he is treated differently. He made a big fuss about this just last week in front of the class, and one of my students (sick of his interruptions) literally said, "Dude, you act differently, that's why." This student (the one who feels I am unfair) is nowhere near as responsible as you, but he is honest in his feelings and not lying. He really does feel persecuted. (Granted, I'm his 2nd teacher for English this year, so he's SOL and not being switched again. He also gets decent grades; it's other issues, like passes, he feels persecuted in; my school isn't like yours.) He really doesn't get why it's not unfair. I know this, and it sucks. But there's nothing I can do to make him see what the other students see (not all of them, but most) that it's totally fair that students get treated as individuals because they are different as individuals.
I'm not saying you're not being treated unfairly. Maybe you are, maybe you aren't. If you have evidence, use it. It's your education. If you don't, I'd go to Rosa and ask her what you have to do to get that AP recommendation you need and what you can do to bring your grades up. She should have an answer. If she doesn't, you need to go to your parents and school admins with that, that you're trying, but that you are not successful and don't know how to be because Rosa is not giving you the feedback you need.