What am I doing wrong

Hi everyone I’m 38 and me and my fiancé have been trying for a year to conceive . I’ve changed my diet I’ve went from 268 to 185 I eliminated my stress became more active I go to the YMCA at least 5 times a week. I’ve never had issues before with getting pregnant because I have other children, in the past until now. I’m following the app. I have learned a lot where I thought my period was irregular but it’s actually not. With my last child after I had him I was on the nexplalon bc and I had it removed when it started to fail. Since then I’ve started having periods. I’ve been taking prenatal, drinking hormonal balance tea & just this time. My body legitimately felt as though I’m experiencing pregnancy and then as the app predicted boom my menstrual came. I feel so defeated and like my biological clock is dead. It’s very depressing. Please no negative comments , but what am I doing wrong?