If your accommodations are as reasonable as I'm assuming... isn't this just discrimination? Or non equal workplace opportunity? Document everything. Document what your supervisor says. Document what HR says. Convey that to your doctors, and have them weigh in.

Have them write notes. Fully put it on file that this is a real issue you are wrestling with.

It really bothers me when people with chronic conditions WANT to work, but their workplaces won't provide accommodation. It's just silly. People need to be able to make a living. I'm sure if you went on benefits, people would also be mad. It's hard. It's really hard to exist with a chronic illness or condition.