I was just wondering if this was your first parent-teacher conference at this school, or if you've had them with other teachers. If you've had sessions with other teachers, how did the level of detail this teacher gave you compare? Maybe the teacher spent most of her prep time focusing on students who need improvement. Still, I wouldn't be afraid to tell the teacher that you're used to getting more detailed information in these meetings, even if your child is doing well.
As a first grade teacher I find this situation very unusual. Most teachers are very well prepared for conferences, and are required to have documentation to support their opinions. You have every right to confront the teacher and ask to see samples of your son's work. If the teacher does not honor your request, then you also have every right to bring your concerns to the principal.
The transition from 6th to 7th grade is oftgen overlooked. In the elementary school grades, teachers have 15-35 students, depending on location and grade level (some states, like AL, have heavily invested, with taxpayer support in limiting class sizes). In 6th grade, teachers generally have 50-70 students. By 7th grade, teachers are caring for 150-180 students every day. At that sheer number of people, I would spend 2 hours every day of the schol year just having parent conferences and preparing for them if I had to meet with every parent, just once. Time and tide await no man, so this would leave me little or not time to plan lessons, prepare materials or grade papers. This is indicative of the increased responsibility being placed on the student to be more self-sufficient in order to prepare them for academic independence that High School will demand in two short years. In one study, college Freshmen were interviewed, and stated they spent 25-50 hours per week on study outside of school time their senior year in High School. Most schools have online grading systems where students and parents can check their students' work. Parents can maintain an active role in their student's academic experience by sitting with them during homework time (2 - 3 hours.night for Middle school) without electronic distractions or phone interruptions. If the parent sits with his/her student at work evey day, he/she will be less likely to not know where his/her child stands academically.