14 days late! Negative home tests!

Levi
Hi guys! I'm now 14 days late! I'm always exactly 31 days a circle, I've done numerous tests, all negative and yesterday i went docs and took in urine sample this morning, waiting to hear from them! But basically I don't feel pregnant and due to all the negatives I'm pretty sure I'm not, so any idea why I'm so late?! Has this happened to anyone else? Thanks!