Ovulation test questions?? Help?!

I miscarried my with my first pregnancy on 11/15- I got my period 12/24- the app says I should ovulate this Saturday 1/11- I have just started tracking my ovulation to make sure my body is working the way it should. I am wondering what people’s thoughts are on these? It seems to get dark on the 6th? Does this mean I was ovulating that day only!? Or is the predicted 11th probably correct?? Thanks