Need advice

I recently stopped taking my birth control in the middle of April and I started my period on time on April 26th. I usually start every 28 days. I haven't started or had my usual symptoms for AF. I haven't started yet and I've taken a blue dyed test the day before I was supposed to start and a pink dyed test this morning both are BFN. I'm​ married and we're using the app to track my fertility window and we are always doing the withdrawal method. Cause I still be pregnant. I don't know when I actually ovulated. Any advice thank you in advance