Depression... Help!

All of my friends, co-workers, etc. are pregnant! I have been trying since October and I have had no luck! Seeing all these people having a baby and expanding their family is breaking my heart. I am happy for them but on the inside I am breaking and screaming "why not me" what are some ways that people that have felt the same way  handled the situation? I am to the point where I just want to stay at home and cry... Help please!