Trying to conceive!

My husband(28) and I(27) have been trying for baby 3 for roughly 6 months now. I am so frustrated and I'm trying hard not to take it out on myself or him! My other littles are 4 and 2 so I've had healthy pregnancies before! When trying to conceive them it happened right away... There was no waiting game! I've recently gone to the OB to get my levels checked and everything came back normal! I know they say it'll happen when you stop planning, but I've tried so hard to "calculate" everything! Any words of encouragement, or tricks from the ladies that have positive outcomes from. Situation similar to mine?!  I really need it today, and probably some prayers.... especially after taking another negative test, which seems to be story of my life!!!