It's not too late! My dysgraphic ds learned a correct pencil grip (through OT) at 8 years old, and my neurotypical dd who wasn't taught a correct grip in first grade learned it with just a few practice sessions at home during summer school when she was 7.

The one thing I am not sure about here though is, why was your dd in OT previously, and is it possible that this remark from an OT re learning grip is related to something specific re your dd?

Best wishes,

polarbear