Why Can't Life be Fair?

I just spent the evening in the Women's and Babies hospital. I sat there as support for my younger cousin, she is only 18. There were so many mixed emotions going through my head. I felt concern, love, happiness, self-pitty and resentment. I want so desperately to be in her place. I want a baby of my own. I am 30, married and would love nothing more then to have a baby. Why is it like this? Why does God give a baby to a child, and not to me? I want to be a good support for my cousin, someone she knows she can count on at all times, day or night, but it is so hard to not break down in tears. I want a baby so bad, but yet cannot seem to lose the weight I need to to continue to try. Why can't I have that will power? I am stuck and feel like I will never be free from this. I try to be so strong and rationalize things. I don't let people know how hard it is to see a pregnant person or a baby, but every time I see one, a little part of me dies inside. I feel so hopeless, so alone. I know that many people are in my situation, yet I still feel this way. I am so depressed.