Why would ff change my ovulation day almost a week later?

Laura

My FF app detected ovulation at Cd 25 after a positive opk on the evening of cd 24 and morning of cd 25 then negative opk cd 26. Between that and my temps ovulation was detected by the app on cd 25. This morning I put my temp in and it changed by ovulation day to cd 27!!! Now I'm freaking out because we decided to take a baby dance break since we were exhausted once I ovulated and I did not have sex on cd 27 or the day after just on cycle day 26 at like 11:30pm (hopefully that was close enough)! Now I'm freaking out that we missed out on the egg and my husband will likely be away on an overnight class trip for 3 days with his students this next cycle. Aunt flow due in 4 days my nipples are so sore and I'm getting pinching and pulling pains where I would get cramps. My cm is also all dried up.