Ovulation confusion

Yesterday I had an internal scan to see if there’s a reason my husband and I aren’t getting pregnant and the guy doing the scan say I haven’t ovulated yet, he said he can see that I’m about to.

The thing is I take OPKs and I had a strong positive about 4 days ago, has anyone else had this?

I think this whole time I’ve just not been having sex late enough as I stop about 3/4 days after I think I’ve ovulated. I thought OPKS were accurate to some degree but this seems way off!

(Crossposting)