Is it possible to miss your surge even if you test 2 times a day???

Ky 8-15-17👼🏼 & 10-28-17👼🏼 Pregnant with my🌈💕
Really wondering because I'm on CD 27 and last week and the week before my lines were getting darker and it looked like I would be getting a positive soon. But this week my lines are lighter. I've been testing twice a day between 9-11 AM and then evening between 4-10 PM. Could I have somehow missed it??