Hi J.,
I am going through the exact same deliberation with regard to sending my son to kindergarten this fall. His birthday falls right on the cut off date (Sept. 10 for the state of Montana).
Like your daughter, he has strengths in some areas and lags a bit in others.
The "Kindergarten Round-up" was last Friday at our school so we went in and had him tested for his kindergarten readiness. It did help me get clearer about when we'll get him started. The final deciding factor will be whether or not the school district changes its program to full-day kindergarten (whereas he won't go until 2008).
At the readiness testing they did a number of activities with him - from running, skipping, hopping, catching a ball, and managing scissors, to assessing the clarity of his speech and testing his eyes, to assessing his familiarity with numbers, shapes, colours, letters, to testing him on his problem-solving and positional concepts, and finally observing his general behavior, cooperation, willingness to try new things and following directions. Whew, we had no idea it would be such a thorough process but, luckily, there were cookies involved!
The kindergarten teacher told me that, even though he is only 4 1/2 right now, he did meet all criteria for kindergarten entrance. More than academics, they really want to make sure that a child is eager to learn, has enough confidence to be away from home during the duration of school, and is behaviorally ready, ie. can sit and listen, and follow directions.
My suggestion to you is to call your school and arrange to have your daughter assessed. You will meet the teacher, see the classroom, and can discuss your reservations with the teacher. As a result of the testing,(which for the kids is really done in a low-key, fun, and supportive way) she will make suggestions to you about what to keep working on with your daughter to increase her readiness. It does sound, though, that you are already right on top of that.
My final two cents, from the info you gave in your query, is that your daughter does seem ready for kindergarten in the fall. A question for you is, "Are you ready?" I looks like she is your baby and I can relate to wanting to not release my kids out into the bigger world of the public school too soon. I am trying very hard to not let that be a factor in our final decision! Darn, I wasn't expecting to have so much angst about school until at least middle school and here I am pulling my hair out about kindergarten!
The best of luck to you!
T.