I understand your feelings also. We've been trying for awhile for another baby. We have a 5-year old daughter. It can get you down. However, I haven't been as healthy as I thougth I was. I started Remicade and am feeling great, so hopefully things will start happening.
Keep trying and keep your chin up! I know how hard that can be when you're struggling with all the "monthly" emotions and hormones. Good luck!