Wow, I don't feel so bad. We are only a family of three, but with DH traveling and DD9 playing sports, I felt like we had a ton of laundry. I probably do one load of whites per week, one or two of colors, depending on the season, one of towels and whatever I can throw in with them to make a full load and one of sheets. (Our kings and DD's fulls make a complete load.) Don't tell my DH that I have less laundry than most, I try to get him to fold whenever possible!
Suggestion for those of you who think your children are taking up too much space in the washer--have them do their own laundry. I think I was about 10 when my Dmom came home with ahamper for my room and Dsis's. From that day on, our laundry was our responsibility. Dmom spent a little time showing us what to do, but it was really ours. I'll bet I was a lot more cavalier about throwing something I had worn for one hour in the hamper when mom was doing wash than when I was!
Good luck!