Following Apps

Kathryn • Hello everyone, my name is Kathryn and my fiancé and I are trying for baby number 2. We have a 4 year old daughter
So ladies question? My <a href="">glow app</a> says I'm due for AF the 12th my other app says the 14th. Now I've always been a 28 day girl. If I go by the 12th that puts me at 26days. Which one should I go by?