Repeat Preformance...?

Ever look at someone you know, see what they're going through, and get worried they will make the same mistakes as you, have the same crappy life as you, ect.? If you never have, good for you. I envy you for not having to watch someone tread the same dangerous road as you, and want so badly to save them, but don't know how. But for those of you who have, you may see yourself in my post today. Because I'm seriously worried about my sister's future, in comparison to mine.
I'm struggling with depression. I'm a cutter, and I cry a lot. I'm not 'emo.' Just because I have problems, doesn't mean I'm like every other person with those problems. Walking down the street, you'd never know these things about me. I act happy, and try to dress so that I look normal. But you can see the sadness in my eyes. It's that puppy-dog look people sometimes get when they're trying hard to look normal on the outside, but are begging for help on the inside. I try talking to my mom, but it doesn't always help. It's not that I don't like talking to her, or that it doesn't make me feel better, it's just that I feel like I have to be careful about what I confess, so that she won't worry about me.
I think I'm pretty close to overcoming it, but then I look at my sister. She hasn't started doing anything drastic as I do sometimes, like cutting, or considering running away or suicide, and I hope she never does. But she does have some of the traits I had when I started down that ugly, dangerous dirt path of depression. She's being distant, and she's easy to anger. She actually thinks my mom cares more about me than her, a thought I remember having, vice-versed, when I first attempted suicide. We live in a very close family, a family that is a lot like those on old-fashion TV shows when everyone's in a good mood. So that's why I feel the way I do, or why she's showing warning signs. I'm praying I'm wrong about this. But if I am right, I pray that she will come to me to talk like I use to when my problems started.

PS, Sorry this was late. I was sort of busy this week. I promise it will be on time on Monday!