So I started taking the First Response opk tests on May 17th and still have not gotten a positive. My last period was May 10th, my cycles are usually 24-25 days so it said to start testing on day 8 which I did. Last month, it was a little late, started on day 28 so I am wondering if that is why I haven't gotten a positive maybe? I have been testing everyday at about 1:00pm but I have been reading that the LH surge can be quick so could I have missed it?! Any advise? Has anybody had this happen? Thanks!