I'm so confused!! Please help...

McKenna
I was using a different fertility tracking app and then found this one. The ovulation days and period prediction days are very different on each app. I'm pretty sure the other app was more accurate to what my body was telling me. I've only started tracking the last three months in order to TTC. Here are my last three periods:
-September 9-13
-October 6-11
-November 2-6
According to my other app, I should have started on November 29. GLOW is saying December 10. I have experienced days of nausea from November 26 to December 1. Then it turned to cold symptoms. I have took 2 tests and both were negative. The last time I took one was December 4. I would be in my 5th week of pregnancy if I am pregnant. I was 5 weeks before I found out I was pregnant with my first child. 
Any tips or advice would be greatly appreciated.