Got brown discharge 6,7,8 day of period with upset stomach !

hi there
i got my periods n they are regular n i m also tryin to get pregnant, this time my periods were kind of more brown in colour n werent too heavy got them 1st 2-3 days n stopped then got spotting on 6th, 7th and 8th day of my period which was kind of worrying as it was for the first time. n had upset stomach with stomach cramps mostly on lower left side of abdomen.. n th test shows negative.. but i think it was too early to take the test.. so could i be pregnant ? n is here any other way i can check if i m pregnant? pls reply