My 11 year old son was ambidextrous in Kindergarten but we had him use his right hand only to practice writing. If he is holding something in his right hand while he is eating, he will use his left hand to eat. If he is using his right hand to move the mouse while on the computer, he will use his left hand to write. His handwriting is only a little better when he uses his right hand. When he is doing piano, he will occasionally play the left hand notes with his right hand. He occasionally rights 5's backwards and they look more like 2's. He sometimes writes P's backwards.
But he started reading at 2 1/2 on his own and could always spell really well. If he sees a word, he usually remembers how it is spelled. We homeschool but I never really had to have him work on spelling because he was naturally good at it and he only worked on it the year he participated in the state spelling bee.
Sounds like me. Being ambi means you can multi-task in a meaningful way!!
In the 3rd grade a very mean and wicked teacher made me choose my handedness for writing.
I still write some letters backwards with either hand. C and lowercase Q are my letters. My spelling is great except when I type too fast.
Mr W was ambidextrous from the first time he grasped stuff. I've noticed that he will mimic which hand I use to eat when he eats. He carries stuff and scribbles with both hands. He tends to favor his left for balancy stuff like steadying himself. He is not dyslexic at all.