BFN to BFP?

So I've held out until the day after AF was supposed to show up to test, been having symptoms all month long, aaaand what do you know, a big fat negative on my First Response this morning. Anyone gotten a BFN at a couple days late that changed to a BFP after a few days? Or should I write this month off & hope AF gets here soon so I can get this show on the road & try again next cycle?