Do you have any thoughts of switching from home schooling back to a public or private school? My children both refuse to accept formal instruction from me or DH, and completely shut down when we attempt to teach them anything that we initiate. They are happy to self-instigate exploration of all kinds of reading, math, and science concepts, and do so constantly, but the minute we try to introduce something resembling actual teaching, they shut down and refuse to engage.
DS6 thankfully has been perfectly willing to accept formal instruction in K, and so has learned to read along with his classmates, even though he was capable of learning at home at age 3. DD4 is thus far showing the same tendencies. I can't imagine trying to homeschool either of them because they are so resistant to instruction from me or DH. We've consulted a private educational counseling specialist a couple of times in the last year, and she said that's a common situation, especially with kids who are perfectionists and don't want to get things wrong in front of their parents - in line with what other posters have responded. So just posing the question of whether public/private schooling would be an option if you and DD continue to have issues with challenging work at home. No matter what, kudos to you for working so hard to meet your DD's needs.