Info on pregnancy test kit box different than what I've been reading here/online - which is fact what is myth?

Hi first of all I am very sad bec I finally took a preg test after thinking I was preg and it came back neg I am surprised to find out. My question is that on the box it isays that it detects pregnancy by 99.8% accuracy 7 to 10 days after conception, and not ovulation like I had been here here on YA time and time again. Is that uming that conception/ovulation are on the same day? Now i understand how tight the times of conception are, that it really must be on the exact day of ovulation. Is that correct? I won't believe any of the other 'sperm lives for 7 days' or 'you can get pregnant any day of the month' myths then, right?