Starting to feel better and look to the future!

So I been having a really hard time dealing with things lately. Everytime i hear of someone else being pregnant, I cringe, I want so much to be happy for them and I know deep down, that I am, but I have such a sense of jealousy that all I can do is cry. Needless to say DP's brothers girlfriend just found out yesterday that she is pregnant, she is only 19 and they have only been together for 2 months. I am sincerely happy for them, but i could not help myself from a total cryfest yesterday morning on my way to work. I just dont understand or get it anymore, will this ever happen for us. I am starting to feel like our whole relationship has begun to revolve around us getting pregnant. I mean I feel like we are arguing everytime I turn around about one thing or another, and lets not even talk about our sex life, that has pretty much become not existant. I just dont know how much longer I can do this. My emotions and sanity are starting to wear out. Its makes it worse when a dr. tells you that there is nothing wrong with you. I mean i had the blocked tubes, but that has been corrected, so I just knew last month was gonna be it for us, and of course it wasnt. Its like negative tests and AF is no longer a disappointment, I have become numb to the whole situation. It really dont affect me anymore. I feel like such a let down and failure. I believe we will try 2 more times at home, and if it dont happen, we will have to move on to something else. I guess........