Our daughter is similar in age, end of Sept birthday and the cut-off for kindergarten is 12/31 except for privates, 9/1.
She is also small, tracking 25th percentile in height and weight but she likes to play with older kids, being in a mixed age Montessori. But I cannot imagine holding her back. She already knows the kindergarten curriculum. And a child will get bored.
From my own experience of acceleration, the size thing really isn't a big issue. But boredom from the classroom material is.
I am not keeping my daughter back.
Ren
