Can someone please help me?

I am not very good at knowing when will I ovulate. So I had the app Ovia and I put when I last had my period and according to the app I’m fertile starting tomorrow until the 27 and I ovulate on the 25th. I’m not sure if that’s right. I got my period this month on the 11th at around 10am. It was not as heavy as it usually is, Barely had cramps when usually the first two days are painful, And It kind of finished on the 14th, On the 15th I had light brown spotting. So is the app right? Or When do I ovulate?. If so when should be try? Me and my husband are trying to conceive, We had sex on Sat 20 and Sun 21.