The school should be a relatively small one, where children are allowed the freedom to be themselves. Perhaps a Monetssori school will best fit this description, though many of them use the Montessori system only in the preschool years.
You should keep giving her warm support at her level and not be impatient with her if others her age have more advanced abilities. Having a kind teacher will be a requirement, but I do not see that parents have a choice in such matters. Maybe letting her spend one more year in a Montessori system would be a good idea. Talk to her teachers and decide.
Get her interesting games that she can engage in as well as music and art materials at home. Spend time with her talking to her and listening to her. Avoid the generally noisy and confusing TV. She can grow up to be like other children if she is given tender loving care now.