so very sad

well, I am really sad and don't have anyone to talk to and so my blog is going to be my way of venting right now. I don't think anyone will read this anyway so I can say whatever I want.
I remember hearing a story that my mom once saw my grandmother trying to commit suicide in the bathtub. I couldn't believe the story. If you knew my grandma you would know that she was the most amazing woman, and she was so sweet and loving, and I can't believe that she could have ever been that low or sad.
Dave and I have been trying to start a family for 3 years and we are getting very frustrated, I now know what low feels like. This past week we had 2 couples that we know tell us that they are expecting and as much as we are super happy for them, we are totally frustrated. I am frustrated that people don't understand what we are going through. I am frustrated that it is so easy for some people and so hard for others.
I am frustrated that even though we would consider adoption we can't afford to. I feel like I am STUCK, I can't seem to get pregnant, can't afford to adopt, can't do anything. The one thing that I want so much is the one thing that I can't have.
I am trying so hard to look to God, trust in Him, cry out to Him, but what does that do? I don't know. I feel like I can't breathe. I read in the Bible that God said to "be fruitful and multiply" and that "children are a blessing" and I believe those words, but I see them happening for everyone but me. Why?
So, I still have to go to work everyday and put a smile on my face, and pretend that life is great, when I don't feel like I can go on anymore. I have to listen to everyone talk about their kids, grandkids, and everything, and hearing them ask me, "Do you have any children?" I just wish that I could say yes. I wish I had pictures to share.
Why is this happening to me?