Sorry should add that she can't read CVC words fluently, despite being able to sound out larger harder words
Mahagogo5, this really resonated with me so I wanted to give you some hope. Dd4.8 was exactly here 4-6 months ago. 3+ years ahead in math, able to spell and read long words but struggling with simple Cvc words. When I went for k screening at public school, they used her non-reading as an excuse for not being able to provide any acceleration in math. I, like you, was at a loss on how to bring her reading to at least end of k level. Fast forward now, dd is fluently reading beginning of second grade level. I wish I could tell you exactly how it happened and what I did. Alas, it just happened on its own. She went from a struggling, disinterested reader to a fluent one in a matter of weeks, increasing her difficulty level on her own. You might find yourself in the same situation in a couple of months or maybe even sooner since you mention the cognitive growth spurt. All the best with your decision.