I just don't understand

I really am having a hard time understanding what is wrong with me. Or if I did something to cause this....or to deserve this. I just want to be a mom. I just want to know what it's like to have a baby. To go shopping for baby stuff and know that I'm going to get to bring it home. To know that I have someone to bring it home for. I don't think I'm asking for too much. Just one would be great. That's all that I want. It's all I've ever wanted. I want my family to be excited and come visit me in the hospital to see my baby for the first time. Why can't it be me? Everyone else is having success, but of course, not me. I don't get it. I'm so happy for my friends, but I am so brokenhearted. We've been trying for 12 years....this is getting to be too much.