Ovulation testing

Madison • 20✨ Army Wife💍🇺🇸 Rainbow baby 11/23/18🌈👶🏻💙

This is our first time ttc so I’ve been testing my whole predicted ovulation window. Occurring to the app I’m 3DPO (CD16) which I know I’m not because this morning I finally had a positive ovulation test. Has anyone else experienced the apps being wrong?