Accurate fertile days?? Help!

Hi there. My husband and I are trying to conceive and I'm trying to find an app that provides a correct prediction of my fertility and my most fertile days. I love the glow app and have been using it for a while to track my periods but I did download some other fertility apps to see how similar they were. I found that two other apps predicted my fertility to start five days after my period where the glow app predicts it about ten days after. Does anyone have an experience with this and the glow app? Has it been accurate for you? We really want to make sure we are trying during my fertile days. Thanks!