Can you ovulate a week after getting a positive OPK?

Kaysee
I was tracking my ovulation with OPK in March. I got a positive CD16-19 which would of been the 10th-14th. I found out I was pregnant on the 22nd. When I went in for my scan at 9 weeks she said I looked closer to 8 and probably ovulated a week later than I thought. Which would of been around the 17th-21st. I just don't see how that's possible since I got a positive on the 22nd at 5 pm and it was a pretty strong positive?