Due date calculation. Is this possible?.

My LMP is jan 16 and according to it , i was 12 weeks pregnant on April 9th but in my scan report it showed that my gestation is 12.6 days... which is 6 days in advance ..How is this possible ?? ...Usually the gestation age will be calculated from the time of conception which could be on the date you ovulate (i understand ovulation day could vary) however , according to my scan report it looks like the gestation age is more than my LMP which is advance ie. january 10th where as i got my periods on jan16 followed by positive pregnancy. 2. For the record, on january 10th i noticed one drop of blood. so does that mean on jan 10th i got implantation bleeding followed by periods in 6 days (jan16) followed by positive pregnancy... becos, according to the scan report , it exactly points to Jan 10th which is 12week .6 days and not 12 weeks . 0 days... please advise