You seem to put a lot of faith in numbers from standardized testing being an indicator of future placement. Here is my opinion for what it is worth: when a child is grade skipped, she might need a long period of adjustment - there are a lot of factors involved - new levels of expectations from teachers, harder academics, older classmates with whom she needs to figure out relationship dynamics, higher level of executive functioning skills, more rigor in homework and tests, etc. etc. It is not unusual for a grade skipped child to not perform well immediately after the skip. Also, her scores are NOT poor - anything around 80% and above shows ability to keep up with the majority of the classroom. Do not compare your child with yourself - each child is unique and has their own strengths and challenges. There is no educational neglect involved if a child skips a grade and gets above 80% in scores. When I request a grade skip for my child, I do so because he consistently scores 99% in all the tests - this is an indictor to me that he has mastered all the material for his grade. If my grade skipped son scored below 90% in the tests in the new grade, it is a rough indicator to me that he has room to grow and improve in that grade because he needs to master more material to get a perfect score - I actually think that it is a good placement when that happens.
You might want to provide some fun reading materials for your daughter to read in her free time if you want to work on her reading levels.