Hello ladies, I've downloaded this app about a year ago, but then end up deleting it🙃But i am back…

Hello ladies, I've downloaded this app about a year ago, but then end up deleting it🙃But i am back because my fiancé & I have been trying to get pregnant already & so far no luck😔I still dont understand the whole fertility days & ovulation days either. My period normally lasts for 7 days & I've heard that the highest chance to get pregnant is after your period ends. If you girls have any tips that'll be great ladies, i would highly appreciated💕