Welcome here.
Individual IQ and achievement testing is the way to go. It will give you more data and you will sort of know what you are dealing with
I would definitely try to get one on one, see if the school will provide it for you, if not and you can afford it, have her tested. The data may help you to get more accommodations from the school.
If your teacher is cooperative and you are able to find a plan which works even if it's for 6 weeks only, then may be you and the teacher should agree to meet every 2 months to re-evaluate the situation and try to find new solutions.
Good luck and again welcome here
