I took this test yesterday and it came back negative. I had reached the recommended 3 months (90 days) The directions said to swab the upper and lower gums only once, otherwise the test could fail. I swabbed once, but I only got the front of the gums and not all of the way towards the back of my mouth. I also don't think i waited the recommended 30 minutes after eating (I waited at least 20 min, maybe more). Would this still be an accurate result?