DRUG TEST

Hello so i smoked pot on the 24 of october. I am so so scared i'm gonna get drug tested! i drank so much water the day after and continued to keep drinking water for the next week to flush it out. i took a drug test i got from walmart, it was a pretty nice one. it was like $15. it came out negative thank goodness, but i was just wondering if i get one at school or if i take another if the results will be different. maybe i'm just paranoid. but i did only smoke once and it was forever ago.