My experience is much the same. Mother taught me reading/arithmetic with flash cards, was promoted from Kindergarten to 1st Grade, private schools until 5th, switched to public school reading at University level. Of course being smart, and the youngest in the class, makes you a target, not popular.
I got to the 7th grade and was put in the retarded division. I could not read or do math. My parents took me aside and taught me to read and write. The next year I was placed in advanced division and never looked back. I am dyslexic but the public school called me lazy and stupid and punished me.