I'm confused 🤔

So I was expecting my period around 4/13/16 my previous period was 3/16/16. I know that glow is only a prediction but... I logged that my period was late and the app has changed my period start date to 4/25/16 and then it updated to 05/20/16 then back to 04/25/16. Not exactly sure why??? Well even more confusion I've taken 4 pregnancy test so far 2 negative the other two well the pink ink just bled across the entire window and I'm unable to make out the results just looks like pink running mascara?? 😭😭😭 I recently miscarried in February and I wasn't expecting my period to be late so when it was I was guessing I was pregnant now I'm not sure what to make of this and I plan to test again tomorrow so far I've test Friday, Saturday, and twice Monday (today). Also I do believe I ovulated later than the app predicts, also my period is 25-26 calendar days apart. Ovulation possibly 4/8/16. Any advice? Anyone else experience their glow app making flip flop predictions?