OPKs as Pregnancy tests? Anyone got a BFP following this?

Hi ladies

We BD'd every 2nd day during my fertile week.

I got a +opk on CD13 and believe I ovulated 2 days later on CD15 (Saturday 30th May) purely because I experienced mittelschmerz pain on my right side early 6am Saturday morning.

However, I have been getting "flashing " smiley face EVERY DAY since CD19 (last week Wednesday) up to today which is CD25.

I took a pregnancy test with FRER from yesterday, Monday, CD24 and today CD25 only to get BFNs disappointingly, where I should be 9DPO...but I've also heard that +opk could be so where there is a positive pregnancy...

anyone with experience of / opinion on this?