How old was Laura Ingalls Wilder when she moved to the Kansas Prarie?

When Charles Ingalls moved his family to the Kansas prairie, Laura was two years old, and she was 3 1/2 when they returned to Lake Pepin. The stories in "Little House on the Prairie" are the storied Ma, Pa and Mary told her - she was too young to remember. She portrayed herself as 5-6 in the book, because she had already established a timeline in "Little House in the Big Woods" that she had to stick with. Beginning with "Plum Creek", she is back to describing herself at her correct age. Also, "Prairie" has Carrie as a baby making the trip with them. Carrie was actually born in Montgomery County Kansas shortly before they left to come back to Wisconsin.