Hey ladies i have a question for those of you who use OPK's. When you get your + OPK how long does it last??? 1 day 2 days???? I test 2 times a day the morning and the night. i got my positive in the morning and again at night but the next day in the morning it was negative. Also im wondering if testing in your stream of pee or a cup of pee makes a difference or not. i got my two possitives using a cup and my negative testing in my stream of pee. any help or info would be great