Not sure where to post this

Maranda
My sister who already has a daughter. (Just turned two in August) just told me she is pregnant. 
When I found out about my niece I had lost a baby in October when she told me in December. Now I've been TTC for almost 4 months and she is pregnant once again and not wanting it. I'm so bitter and angry about it. 
Why can't it be me. Why again does she get to have a baby she doesn't want when all I want is a baby.