Ok getting worried is she pregnant?

ok so we did it lets just say 1 week and 3 days before her period and its comes on either the 11,12,13,or 14 and so we waited till the 14 and it never came so we waited till the 20th it never came then we went and bought a first response test and she took it it said negative so then we waited a week later and still no period so we took the test agin still said negative then finally it cam on the 5 of this month but kinda in small drops then a lil more and it stayed only a lil bit of blood we took a nother test still nothing so im getting worried is she pregnant