Well, if the teacher is suggesting that suspected autism may be interfering with your child's emotional development to a great enough degree that her assignments need to be limited to prevent damage, I think that a full evaluation is in order.
Teachers aren't permitted to diagnose. If the teacher really thinks this is an issue, then a referral for a disability evaluation through the school should have been made immediately, and should be made now that it has been brought up to you as a reason to deny advanced work. Such evaluations typically include IQ and acheivement testing as well as other relevant diagnostic tests. These tests may well reveal that your daughter is exhibiting such perfectionism because she is seriously underchallenged.
Make sure whoever evaluates your child has read
this book, or is at least familiar with the material in it.
