I can certainly understand your desire to refuse medical treatment and yet want the psychotherapy. While the mainstream standard is typically to use a combination of medicine and psychotherapy together for the best results, there is also emerging evidence that some psychotherapy approaches may work better than this treatment as usual as these references on positive psychotherapy will attest to. On the other hand, there are legal rights that you should become familiar with in both your state and as a patient being cared for.
Naturally, I can’t give you medical advice, but I am certain that a physician had to evaluate you for your Social Security Disability Insurance claim. It might be worth it to contact him or her and explain your situation to see what might be recommended.
Also, the fact that you are pregnant means that you can get the opinion of the OBGYN specialist to weigh in on helping you with the medicine decision. You could also ask to be reevaluated by someone else at your clinic who might see the risk during the final trimester as evidence enough for them to honor your request.
In any case, I strongly recommend you find medical help to help you safely come off the medicine. You don’t want to do something unknowingly that might be dangerous or difficult. A medical opinion on this is essential.