6 DAYS LATE? BUT NEGATIVE TEST

i'm 6 days late for my period, i've taken a pregnancy test every other day(clinical guard from amazon) and there all clearly negative. i've been cramping off and on for 6 days but other than that no sign of my period and i'm also have A LOT of watery like discharge (sorry tmi) and my nipples have been sore the whole time. my period always come on time they have been longer sometimes like 2 weeks but i'd still get my period when i was supposed to. could i be pregnant and the test just aren't picking up the hormone? i just wish i could get a positive or my period so i'll know something.