Doc says that luteal phase cannot be longer than 2 weeks but i ovulated 30 days ago with negative pregnant test.what could be the reason ?

Different reasons: The question is a little confusing but i think you are stating that you believe you ovulated because a home lh kit was positive and you had time intercourse but are not pregnant? You may not be pregnant because you actually didn't ovulate. Home lh kits, if that is what you used, can have false-positive tests. It also can be that you ovulated but conception for many different reasons didn't occur.