Now I'm just confused?!

Think I have to many TTC apps on my phone now! Glow is telling me my AF is due 19th and I have another app with the exact same info in that is telling me AF is due 21st. I know it's only a couple of days difference but when your on your TWW and waiting to test those 2 days are crucial! Now if AF doesn't show on the 19th I'll get my hopes up but then it'll probably come on the 21st like the other app says! Grrrrrrrr! The ovulation dates are  different too so now I think I may have stopped BD to soon!!