Anon, what judimary is talking about is the average. Do you know exactly when you ovulate? Some women ovulate sporadically, so they might be able to conceive at any time during a cycle, whereas other women will ovulate right at two weeks. When you ovulate and when you have sex can also be a week apart and still conceive. When you conceive and when you implant can be a few weeks apart. In your case, you could have a delayed cycle and negative tests if your body hasn't built up enough hormone because you implanted later than you're thinking you did, or you could have a delayed cycle because you're very hopeful that you might have conceived, or you could have a delayed cycle because of something not pregnancy related.
at 10:28 PM on May. 22, 2011