Ovulating or PMS?

Okay so my last "period" started on May 13 & went off on May 14. Weird I know. I stopped taking my birth control pill maybe a week or 2 prior so I chalked it up to that. Anyway, the app said that this past week was my fertile week & it ended yesterday. Why is is that I'm experiencing ovulation symptoms now? Is it possible that the app is wrong & my fertile window is now instead of last week?