Karen, the principal is wrong. You have made a referral for evaluation in writing. The school is responsible to request consent from you for the evaluation "promptly". 9-18 months is not promptly. Once you sign consent for evaluation, they have 60 days to evaluate. Go in and ask to sign consent.
Also, you might want to talk to the teacher about the way she is grading your D. Her grades need to reflect her ability and if she is changing them based on her attitude, they do not. Her need for evaluation as far as the school is concerned is based on her progress which is measured by her grades.
You could also call the District Special Education Director. Let them know that you've made a referral and would like to sign consent. Never hurts to go over the school if they're not cooperating.
From experience, I can tell you that if they don't do the evaluation this year. You'll be starting all over next year and you'll risk another year going by with no services. You have to be really pushy. School districts don't like to do it.