How reliable is a BFP on clear blue digital?

Joh
Hi all,
​we're first time TTC for 9months and this morning is DPO 14 (AF due tomorrow) and I got a faint line on a cheap ebay pee stick. And then an hour later I took a clear blue digital test (one of those conception ones) and i got a "pregnant 1-2 weeks"!!! We're so excited, but part of me is wondering how common false positives are since AF is only due tomorrow? I know it's possible to have chem preg etc but just wondering other than that would the test be reliable?? Can we really celebrate? Ha. Thanks