First time using opk.

Zoe • Me(21) ♥ engaged
This is my first month using opk. I'm CD 16 today , I got an opk with one faint line on both yesterday and today...glow says my highest day is tomorrow.. Is that possible? Could I have already Od? My cycles vary between 28-30 days but was 34 last month..? Confused.. Any help would be great thanks x