Ovulation kits accuracy

What is the consensus on clear blue digital accuracy?
I started on day 6 as directed, got a "peak" on day 7. No CM signs so I restarted it again on day 9 was low, days 10 and 11 got "high fertility", day 12 "peak".   I'm on month 10 ttc. Getting frustrated with the kits. Last month I used a different brand kit and it never gave me a +. 
Thoughts?