Help so confused

Samantha • Me and my boyfriend have been together for almost 8 years we have 2 kids together and ttc #3 after a MC 🙏🏻👶💗💚💙
When I started using this app I put in when my last period was and it said it would start on the 26 my period all ways lastes 5 days and comes every 28 days but I uesed sum ovulation test and it changed it to the 30 of this month so which one is it I don't know anymore