Now, unless her kindergarten teacher "testify" or you find specialist to testify that your daughter is not ready for 1st grade, she has to go to 1st grade.
I just realized Connecticut cut off date is Jan.1, so, in theory, 1/3 students will go to 1st grade before 6th birthday. From your post, seems your D B-Day is around Oct., she is not really the youngest in the classroom.
Co ask the question: what makes you think your daughter is not ready? (I personally think teacher/education expert knows more on how well a kid can do in a classroom setting.)