Ovulation changes

Hello I’m knew to the community!

I have been married for 17 years and have had 3 miscarriages, all 3 pregnancies have been possible through fertility treatments. Our last miscarriage was in 2016. Since then my husband and I decided to not try any more treatments and trust God for a miracle.

I started tracking my basal temperature and using and ovulation kit last week. I’m confused 🙃 the ovulation date keeps changing after I input my ovulation test results!!! Is that normal? Yesterday I finally got a positive reading and today is negative 👎🏻 any thoughts?