I was also noticing that comparatively low processing speed, along with the low score in coding. I think you have good reason to pursue a neuropsych workup. I think she looks like a good candidate for the 2e kid who never gets recognized due to being smart enough to cover up her LDs and LD enough to appear "not gifted". Parents know their children best, and if you have always felt she is gifted, then chances are high that she is.