Hello, Cho. I know you're not likely to heed any advice I give you, so I'd just like to preface my comment by telling you that my knowledge of grammar is every bit as extensive as yours, and I'm older than you. Since I'm both a Muggle and an American, we can't compare academic achievements, so you'll have to find another way to decide if my opinion is valid.
That said, you really need to stop being so self-centered. I mean, have you even looked at Marietta lately? She's miserable; you can't go on pretending this is about exams. Try spending a little more time with her and a little less time with Michael. Do you really need a boyfriend after that whole Harry thing? Did you really need Harry after that whole Cedric thing? Slow down. It's okay to be single for a while; in fact, it'd probably be good for you.
Honestly, you'd be a lot happier if you stopped trying to impress other people so much.