I agree with the PP. Once you get a positive OPK it only means your surge is happening. If you look at my chart in my signature you'll see I got two positive OPKs on days 16 and 17, but I didn't ovulate until day 19. If it doesn't happent his cycle, maybe consider charting next time so you feel more confident about when you're ovulating. It's also possible to have a surge and then for your body to not ovulate yet, but try again in a week or so. By charting you can feel more confiden in what's going on.
Good luck.
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