Am I a bad person for thinking that ?

I don't think you are a bad person, and I totally understand. I think you should maybe share less information with "Susan" in future.

I agree with Tes yeux noirs and will add that not only are you not a bad person but correct to be irritated. See if you can tell her the truth that you don't want to copied about what you want to become proficient at - without being mean or angry. You are simply explaining how you feel. It's helpful in life to learn how to be straightforward about what you think and at the same time not hurt people. That can be tricky to do if you are angry. She likely means well and doesn't have a concept of how annoy the copying would be to someone. Especially if it's not one of her interests, copying you is quite a clingy thing to do.

Thank you for answering so quickly.
Yes she does get clingy sometimes. I thought about talking to her about it but it's just that she's getting me angry these days and I don't want to end up saying the wrong thing. Like for example she talks about herself saying that she'll become very rich when she's finished her studies and says that she'll buy me something that I want but can't afford. I know the field she'll be working in has better salaries, but that doesn't mean I won't be able to work or get a good salary. She's really been annoying me a lot lately. I don't know if it's just a phase and it'll pass (because every once in a while I feel like that about her, I question our friendship and then I change my mind), or if I should just stop being friends with her. But then again I wouldn't know how to do that : may be become more and more distant and that way it's not very direct ? I'm really lost to be honest. Is it normal to have these feelings about a friendship often ?

Everyone annoys a friend once in a while, it's quite human as we all have differences, but she seems to have a "tin ear" about people's feelings.

I would have to set her straight about how I took her behavior, but that's me. If you don't want to tell her how you feel, I see it as difficult to keep dealing with her in any kind of best-friends way, and would then pay attention to other people I liked, increasing distance.

As an oldie, I can say that some friends stay close friends, but most tend to move along with life's changes over time.