Feeling discouraged

We've been trying for three months... are intimate during the fertile window... still no positive. I started my period three days early and it has been lighter than normal with no cramps, but I think AF is giving me a break because I'm so upset. I thought for sure this month was it because I have been so uncharacteristically moody. Here we go again. I was hoping so hard for this month as it's the last month I wouldn't have to take extra time off work (teacher).