#1 - The school cannot ignore his needs just because you don't medicate him. They are still legally required to evaluate him for special services he might require. I am just learning my way through the IEP maze, but I have figured out that much. One source to learn about the process is wrightslaw.com
#2 - My younger son has bipolar and adhd. We homeschooled for 5 years - this is the first year my kids are in public school. After we found the right med to get his mood swings and rages from the bipolar under control, they wanted me to try him on a stimulant. I was scared, because I knew it could induce mania, but we tried. He was 7 years old, doing 2nd grade level math, but kindergarten level reading and struggling with that, and had been diagnosed with dyslexia earlier in the school year. The very day he started the stimulant, he could READ. This wasn't a matter of calming him down or controlling his behavior - this was a matter of correcting the misconnect in his brain so that the words stopped jumping all over the page.
Remember - this child was homeschooled, had one-on-one tutoring from a loving parent, and still needed that help. He wasn't getting lost in a busy classroom with not enough attention from the teacher. And that was not enough to fix the problem. He still needed that med. He was so happy that day that he could read, and he realized it was the medication, and he realized he was not dumb, and it was just the spark he needed to get excited about learning.
#3 I know someone else already suggested this, but homeschooling may be just the option you need. You will be assured that he is getting one-on-one tutoring, and you can control his environment to make it easier for him to learn. It is a wonderful experience.
#4 Not all teachers are like that. I was very hesitant about using the public schools, but everyone I have dealt with has been absolutely fantastic. They have gone out of their way to help him, and to communicate with me, and to keep things consistent between home and school. They truly are partners with me in educating my son.
Having a special needs child is challenging. I wish you peace with whatever decision you make.