Hi SabrinaT - no professional experience here, but I also have an 8-year-old who was also scoring extremely high on school testing, who is a very advanced reader. Thanks to the advice of others on this list, this lead us to have DD8 take the ACT Explore test through a Talent Search (it sounds like this will be the last year for Explore, before Talent Searches switch to another test, so you may want to try this soon if you decide to go this route). Without any prep other than one practice test (the one suggested by and offered by the Talent Search), she scored extremely well on the Explore. This lead us to an IQ test, and then DYS. The school now might finally be seeing that she has some academic needs that are not met in its typical classrooms - time will tell, but things are looking up!
Testing gives you information which may be useful in advocacy. Some families don't need it, but we were feeling like DD's needs were not being met.
Welcome, SabrinaT!