I need to ask an anonymous question.

I have been ttc. My last period was April 18th. I went to the doctor for something not related to ttc but while I was there they did a urine test and it came back negative on may 4th. I was supposed to ovulate from may 1st until may 7th but this month I had not been keeping up with it at all. My periods had been consistent for the past 3 months though. Then during this month our family has been going through alot of personal issues. I thought that the stress made me late. Yesterday I realized though that I was really late. 17 days late. So I tested. And it was positive.

My question is when woukd I have ovulated? This app says I'm already 7weeks?? Bc of the last period date. But if that were true wouldn't I have came up positive on may 4th??