DPO questions

Viviana
Im confused. How do I count how many days past Ovulation? <a href="https://play.google.com/store/apps/details?id=com.glow.android">Glow app</a> giving 23 AF(10dpo) And FF app giving 24 AF(9dpo). I took a test today and got a BFN ☹️. Am I out? or still too early?