TTC for 6 months

We've been trying for number 2 for 6 months now. My cycles seem to be all over the place, but I'm ovulating each month according to the clear blue advanced ovulation monitor. Each month I get my hopes up and show signs of pregnancy but then AF shows up. Right now, I'm 6dpo, my bbt has slowly elevated every day since O, but I started spotting tonight and am starting to have cramps. I'm not due to start until Sunday. I'm not sure what to think and it's exhausting each month being so let down.