Ovulation date changed 🥺

So I had a long cycle last month 35 days. I went off birth control in May and had a normal 28, then 35 day cycle. The app adjusted my ovulation date accordingly and my fiancé and I planned around it. Well all the sudden on CD13 I get a positive opk. We quickly get busy that morning. Later the opk is even more positive. Get busy the next day. And then that night it’s negative. Now I feel so sad bc I think we missed our window bc we only BD on the day of positive rest and day after. And I hate this waiting now to see. I love this app but I’m starting to see the flaws when your cycles are irregular. I’m hoping after 3 months off BC I can start to figure out some normalcy. Has anyone had this happen before? I’m thinking of continuing to test to see if that was a LH surge without ovulation and maybe I’ll have another? Any thoughts would be so appreciated. Baby dust to all!