Always BFN

I'm so used to seeing nothing that when it finally comes up as something I'll probably cry and won't believe it. AF due in 5 days really hoping this is the month. I'm getting really upset borderline depressed that I can't get pregnant. I know people have been trying way longer than 15 months and I don't know how they do it but I'm just about ready to stop trying. I get so sad that I can't give my husband a child. He has one from previous relationship but it's not the same as if we were to have one I want to have a family of my own and feel as if it's never going to happen.