Clear blue digital ovulation tests

Brittany • Just got married in March. Expecting our first baby April 2016! Already a momma to 3 fur babies.
I've used them for two months, and figured out that I have peak fertility on day 11. However, all days prior, even day 10 show low fertility. Is it not showing high fertility because I'm only testing once a day? Is it normal to jump straight from low to peak?