She is a bit slow in her work output (is a fast reader, though). And I have a running joke with my husband that she is spelling and grammar disabled!
It's jarring the disconnect between what she reads and understands/can discuss versus the quality of her written work.
Southlake - this sounds like it could possibly be dysgraphia. The ds I mentioned above with a similar score profile is dysgraphic. There are different types of dysgraphia, with different skills impacting (spelling etc). You can find a list of the types by googling around - I think there's a good list at NCLD. Sorry I don't have a direct link to post at the moment.
Re what to do to help - the first thing is to find out if possible what is causing the relatively low PSI subtest scores. It will be difficult to determine this without a bit of extra testing to differentiate between fine motor and visual issues. If it's a vision issue, you might be able to find some gains through vision therapy. If it's fine motor, you might also find that OT would be helpful depending on what's up. If it's truly dysgraphia, chances are you'll also want to start your dd using accommodations (maybe you already do and don't realize it). Let her type or audio-record her academic work.
Is she heading back to b&m school or are you going to continue homeschool? If she's heading to b&m school, or if you're planning on any standardized testing in the near future (or even in the semi-distant future), it would be a good idea to get an official diagnosis (if there is a true challenge) and to have a game plan for accommodations in classroom and on testing. Understanding is the first step, and after that documentation is everything

Best wishes,
polarbear