End of the fertile window

Elizabeth
So I'm nearing the end of my fertile window Think it's about 3-4 days until the end and I've been using OPKs. I haven't even gotten a positive yet! I've been cramping like I'm ovulatating but nothing on the test... Im losing all hope of ever having my second baby. Just keep crying all the time. Every time I see a baby, my heart hurts. 
Going to the doctors tomorrow to see what I can do. This is really getting me down 11 months of TTC. When it only took me 3 months for my first. This app helps a lot as you can find all sorts of information out that you don't know. I don't know how anyone who has been trying 2+ years for a baby has kept there sanity. I'm a wreck here.