5 months in to TTC and last month I thought I'd try the clear blue ovulation predictor kit. Last month the smiley face came up on day 7, day 13, and days 18 & 19. This month, with a new box of sticks I'm now on day 20 and have had no smiley face on any day. I'm definitely using the kit as per the instructions. Any ideas as to what is going on? I am confused.