pregnant or just delayed?

last mens ko po is nov11 - 14, nagcontact kami ni partner nong dec 11 (withdrawal) expected period is dec 12-13 pero wala pa din dumadating until today dec 19. nagpt ako dec 17 and 18 pero both negative,. regular po ako at 28-30days cycle lagi everymonth. is there possiblities na preggy ako at masyado lang maaga ung pagtest ko ng pt?