Lh surge time window so small?

verena

Hi everybody, I just started doing opk tests last month. Because I switched the test and did 2 tests in 1 day, I got 1 positive (for 1 afternoon/evening) last month. This month, I tested once a day, and I got back no positive at all. Can my time window be so

small that I missed it, or did I not ovulate? Has anyone similar problems? Do you test multiple times a day? How large is my time window for sex? As small?