Not doing so well

Laura • 28 yrs old. TTC #1. TTC since Nov 2014. never conceived before. just want my own little miracle.
Well it's offically been two years of TTC. everything is normal and I can't get pregnant. I can't do this cycle anymore. I don't wanna cry all the time and I don't wanna watch the world around me turn into parents while I crumble away in sadness anymore. I just want one child. I don't need two or more. Why can't I have one ? Just ONE. Why was I chosen to go through this? I want to throw in the towel but every month there's a reminder that I'm not capable and not good enough. Trying to turn my negative thoughts into positive ones isn't easy. I'm sorry.