Cd22 still low on clear blue advanced digital

Mackenzie
I'm using clear blue advanced digital tests and I've been receiving a low reading since CD10. My cycles range from 28 one random time to 45 one random time in the last 2 years generally closer to 32 days, +\- 3 days. 
Anyone else??
I'm starting to think something's wrong. It's only our 5th cycle trying, and I did get a positive cheap test strip a few months ago, not last month but I stopped by cd22 this month I'm going to continue testing.