It may be the case that art is a good subject for you to be doing but you need the teacher to be more understanding and accommodating of your needs. It could be an equal opportunities issue in the sense that the teacher may need to adjust how she is working with you to help you do your best in art. If you are good at it but are being given detentions due to outcomes that happen as a result of the adhd then the teacher needs to discuss any reasonable adjustments that can be made.