Should I test again to double check?

So I did a preggy test 3 weeks after I had sex and one day after my expected period. It came out negative. (But I think I had early period as it filled my pad and was very dark brown...so I don't think it's spotting?) Should I do another random test in the next week to make sure I'm not preggy? I'm just feeling something weird down there...like I'm about to have my period but I'm actually not. And my next period is due in March 1...but I am facing many discharges. And btw this was my first sex!