States of mind when TTC sometimes

When you know your exact fertility window month on month and you do everything right but still nothing is happening. How frustrating is that. How much does it make you doubt yourself and your capability to have a child ? Sometimes the bad days can be really bad and one has to try hard to cheer up. The worst is when ur AF comes and you feel like u wanna kill everyone around esp. DH. God sure has made women string and complex : )