Mixed feelings...

So my little sister is pregnant. She's 16. I couldn't be happier for her. I admit I think she was really stupid for trying to get pregnant this young but oh well. I'm JEALOUS though. I've been wanting a baby for quite a while now and I've tried and got no where. Had a miscarriage and the man who's baby it was said "oh. That sucks" with no care at all. I dont wanna be jealous about her pregnancy, I'm really happy for her. But it just makes me kinda depressed. What do I do? I dont wanna be a bad sister. I've already let her know that she has all my support and love and that I'll help her with anything I possibly can. Advice?? I know its stupid. Thank you for listening ladies