I can't imagine what you would get from testing that would help you currently. Testing kids that young is somewhat unreliable, so even a huge number or a weak one has to be considered suspect. If you don't need testing, I'd suggest waiting until she's older. She might still be shy and reticent at 7 or 10, but she will likely be much more able to interact regardless of how she's feeling and able to perform closer to her capabilities.
Grinity -- I think you mean SB-V? The 4th edition has been replaced. I think even the SB-V would be suspect at this age just because kids are often quirky and less engaged at young ages which shakes up the relative performance.
Homeschooling will allow you to adjust for her strengths and weaknesses. I imagine those are more obvious to you on a daily basis than any info a test will provide.
